TO THE RIGHT HONOURABLE THOMAS, VISCOUNT FAUCONBERGE.  
MY LORD,  
IT was the saying of a learned, wise, and great Man, of our Nation, that Books of Use ought to have no Patron, but Truth and Reason; And whether or no I have observed this Rule, in devoting this Book to your Lordship's Patronage, will not be much disputed by Any, who have the Happiness and Honour to Know you well. For, whoever understands your general insight into all Kind's of Learning, your exact judgement in distinguishing Truths from Falsehoods, however subtly concealed and plausibly delivered, and your strict Reasonings in all Arguments offered to your Consideration, doth need no other proofs to convince him, that, if You are not Truth and Reason itself Animated, yet (at least) you have them in you, in so eminent a degree, that it can be no Flattery to say, You are therein a Grand Exemplar to Others: nor will the most Scrupulous refuse to embrace, as Authentic and Current, whatever Position hath once received the stamp of your Assent and Approbation. So singular a Felicity it is, to render Nobility more illustrious with Learning; to have long cultivated a fertile Mind, with select Precepts, and useful Observation of Men and Manners; and always to make mature Deliberation the Harbinger to Belief, as well as to Action.  
Besides, the Argument of this Discourse, which now humbly seeks your L ps. Countenance, is much more proper and fit for Your Cognizance, than vulgar Eyes perhaps may judge, when they first glance upon the Title of it. For (to omit, that it leads to the most excellent of all Human Knowledges; the Knowledge of Ones self, which is the groundwork of Civil Prudence) it explaineth the most probable Oeconomy of Nature in perfect Animals; and especially the most perfect and noble of them, Man: A piece of Science, certainly, so far from being Unnecessary to a Statesman, that I dare affirm, None can ever attain to any competent proficiency in the Mysteries of State-principles, or the Art of Governing Men, who is not in some measure conversant in the Mysteries of Human Nature, as well those which concern the Constitution and Fabric of the Body, as those which belong to the Inclinations and Passions of the Mind. And, the Reason hereof is obvious and plain; since the Maxims of sound Policy ought to be derived from the Laws of Nature, at least by way of Analogy and Imitation: & the best way to understand, how to preserve Men in Societies, is to observe, How Nature at first produceth, and afterward conserveth them in their single Persons, or individual Being's. Certainly, My Lord, the highest pitch, to which Human Wisdom can aspire, is, to imitate the works of God in his Creatures: and the most perfect Model or Form of Government, is that, which comes nearest to the Idea of the Divine Constitutions, either in the larger Volume of the Universe, or in the exact Abridgement of it, the Body of Man. This made Pythagoras call Man, the Measure of all things. This makes the greatest Politicians so frequently consult the oraculous Aphorisms of our perpetual Dictator, Hypocrates; and transfer His Rules of curing Diseases of the Body, to the composing Disorders, and rectifying Distempers in the State. This Menenius Agrippa found a happy truth; when He, in a moment, appeased the seditious and mutinous Commons of Rome, only by a speech, wherein He compared the several Members requisite in a well-ordered Common-weath, to those in the Body of Man; and shown the Offices of Those, to be as necessary as the Functions of These. And, this that incomparable Sophy, the Lord St. Alban, seems to have reflected upon, when He said, It was without precedent, that any Government had been disastrous in the hands of Learned Governors; and doubted not to call those, Empirique Statesmen, who are ignorant in Natural Philosophy. I could, My Lord, expatiate in this noble and ample Theme, and permit my Pen to run into a Parallel betwixt the several Parts in a Body Politic, and those in the Body Natural; and demonstrate the near Affinity and Correspondence of them, in their respective Uses, Actions, and ways of subministring to the Health and Conservation of the whole: but that I here speak to a Person, to whom such speculations are so familiar, that I should derogate from the Vastness of his Parts, to imagine it needful for me only to put Him in Mind of them, or (indeed) of any thing else suitable to that place of Eminency, and Condition of Dignity, to which his Virtues have advanced Him.  
Now, My Lord, these my Exercitatitions being thus, in a Twofold Respect, capable of your Lordship's Favour; their Ambition in seeking to acquire to themselves more of Value and esteem, from the Knowing and Ingenious part of Mankind in our English World, by carrying your illustrious Name in their Front; is not only Excusable, but also Commendable, as being grounded on the Law of Decency, which forbade them to address to any other Sanctuary; and which evinceth, that this their applying themselves to your Lordship, was upon due Regard, not upon Facility.  
And, for my Own part; that I have taken this way of Testifying the extraordinary Respect and Honour I bore to your Person and Virtues: this is to be imputed, partly to the Humility of my Condition; which permits me not to be so happy, as to have any better Means, or Opportunity of expressing my Devotion; and partly to my Gratitude, for the many singular Favours Your Generosity long since conferred upon me, which always urgeth me, in the best manner I am able, to acknowledge myself,  
My most Honoured Lord, Your Lordship's Most humble, and most entirely devoted Servant, Walt. Charleton.   

The Stationer to the Reader.  
THat you might be acquainted with the Occasion of the Author's writing this discourse, his Design therein, and the Motives that induced Him to consent to the Publication of it; I have obtained leave of him, to Print also this following Epistle of his to that Excellent Person, Dr. Ent, to whose piercing and impartial judgement, he thought fit to submit his own, as well concerning the Veri●y and weight of what his Papers contained, as concerning the fitness of their Constitution to endure the public air. And this Favour I was the more importunate 〈◊〉 him for; both because it might evidence his Modesty, in distrusting his own Exactness: and because it might appear, it was not only his Inclination, that brought this Book into my hands, and so into yours. Besides, I was not so improvident of my own Advantage, as not to understand, how much of Reputation the Book hath acquired to itself, by passing the Examination of a Man, whose Universal Learning, and admirable Perspicacity in things of Nature, have conspired to render him as competent a judge of such Treatises, as the World affords. This I say, not to assure you, that Dr. Ent found nothing in these Papers, from which He thought fit not to descent; because, the subjects of Philosopher's speculations and Inquiries, being usually very obscure in themselves, it is no rarity to meet with Diversity of Opinions among Them, as well as among the Vulgar: but, thus much I dare avouch, that He dissented but in very few points, and those only concerning such difficulties, that are not yet clearly determined by Anatomical Observations; and that nevertheless, He pronounced the whole work to have been undertaken upon mature Consideration, and done with singular Care, Industry, and Circumspection. And I doubt not but you also will be of the same Opinion, when you have attentively read the book; in which confidence I commend it into your hands, being not a littla glad of so good an opportunity to manifest my devoir toward the advance of Knowledge, and service of the Public.  
Hen. Herringman.   

Clarissimo Atque Ornatissimo Viro. D. GEORGIO ENT, M. D. &, Celeberrimi Medicorum Londinensium Collegij, Socio dignissimo.  
ANnus jam fermè elapsus est (Praeclarissime Vir,) ex quo è Magnatibus nostris Quidam (insignis quidem Hippocraticae familiae Fautor, & cujus, in caeteris omnibus quae ad veram Sapientiam spectant, eruditissimo Animo singularem res etiam Physicas altiùs contemplandi aviditatem, â juventute usque infuderat Ipsum Naturae Numen) quotidiana, mihique prorsus ineluctabili precum importunitate, à me effiagitabat; ut, sepositis aliquantisper, quibus tunc temporis totus incumbebam, fludiis, nupera Anatomicorum Inventa, simul cum celebrioribus Medicorum super iisdem Sententi●s, maximè quae Arti nostrae & luminis & augmenti plurimum attulisse hodie censentur, breuritèr Sibi, atque ex ordine, enarrarem. Neque enim (ut aiebat) otii tantum à severioribus Reip. negotiis suffurari potuit, quantum satis esset perlegendis omnibus, quae de re Anatomicâ novi quid, supraque Vulgarem Genium sublimis, in se continerent, Recentiorum Voluminibus.  
Ipse autem, quò illustris adeò Viri, mihique verè Patroni, imperio, quantum in me esset, obsecundarem; ne tam laudabilem, quâ flagrabat heroïca Mens, in reformatae Anatomes mysteria inquirendi sitim, diutiùs inexpletam relinquerem: quam demandare placuit, provinciam in me libenter suscepi. Mox itaque ad Authorum eorum, quorum seu Industriae, seu disquisitionum Felicitati, nuper as in Medicorum Scholâ Novitates debemus, iteratam lectionem seriò me accinxi; atque ex iisdem denuò quaecunque Maecenatis mei expectationi satis facere posse judicabam, fideli calamo exscripsi: nec vadimonium datum ante deserui, quàm 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 simul in unum (qualis de Oeconomiâ Animali, juxta recentes in Anthropographiâ Hypotheses, ingenuè Philosophantem decere videretur) continuum Tractatulum consuissem; adjectis hîc illic quibusdam Ratiociniis, quae ad caeterorum sive elucidationem facerent, sive connexionem.  
Caeterùm, Chartulas haud citiùs perlegerat Nobilissimus D nus quin, ipsas, non Sibi modo, sed & aliis utiles fore, generosa quadam Humanitatis exsuperantiâ, existimans; ulteriùs adhuc sui in me arbitrii experimentum capere adnixus sit, adque operis Divulgationem ardentissime me solicitaverit, Recusavi saepius; utpote non ignarus, quàm ●xigui-essent pretii hae Lucubrati●nes, apud perspicaciores Sophiae cultores; quámque nihili sit ista Laudis messis, quae ex Rhapsodicâ Scriptione, utcunque fideli elaboratâque, acquiritur: & quò meipsum meliùs tueri possem, varia in contrarium adduxi argùumenta, Dixi nimirum, quae scripseram, in privatum solummodò Ipsius ob●ectamentum collectà fuisse, stylique impolitioris stamine contexta; ideóque summè temerarium fore, si extra privatos cancellos in publicum divagari permi●terentur: pleraque ex contentis, licet Ipsi forsan novitatis specie arriderent, aliis tamen, maximè è Doctiorum censu, jam obsole scere: me denique occurentibus in operis serie aliquibus Difficultatibus, quas vel omninò intactas reliquissent, vel sensu planè diverso explicâssent Emunctiores) eâ interdum usum Conjectandi libertate, cujus me deinceps, post secundas cogitationes, forsitan meritò poeniteret. Sed plane frustrà fui: Is enim, concepti semel desiderii pertinax, contra excusationem omnem aures occluserat. Quid agerem igitur? Hinc Viri Dignitas, & Amicitiae Sacra premebant; illinc Tenuitatis meae conscientia: Contra hanc peccare, temeritatis esset, atque insolentiae; nefas autem illa violare. Hôc Dilemmate obsessus, diu anceps sum animi, donec tandem ea conditione inter nos conventum est, ut cordatum aliquem ex Aesculapii Mystis, in rei decisionem, ilicò appellaremus. Acceptâ itaque semel utrinque aequissimâ isthâc lege; pronum erat, Q●em è Nostratium Doctissimis in Arbitrum seligeremus.  
TE enim, Vir Excellentissime, quem esse eum omnes meritò agnoscunt, in quo Eruditioni summae (sine fuco dicam) summus accessit Morum candor, in ingens Medicinae decus, Nominisque Tui immortalitatem; Quis aut Cordatior, aut Aequior poterat nominari in judicem? Tuum itaque penes arbitrium jam est, ut vel securis Musaeoli mei tenebris, vel petulantis, inque Eruditorum scripta, supra quàm decet, severioris Vulgi Censurae, adjudicetur Hicce, talis qualis est, de Humani Corporis Oeconomiae, Discursus: quem in eum finem ad E. T. nunc misi, vacivis horis (saltem nisi molestum nimis fuerit) evolvendum; non opinionem, sed Oraculum habiturus, quicquid super eodem è Delphico tripode responderis. Spero autem interim, antiquam tuam, & toties feliciter à me expertam, in Tuî Cultores Humanitatem, mihi excusationi suffecturam, quòd sublimiores Tuas, atque in Artis nostrae (quam Dijs ipsismet adeò cognatam meritò agnoverunt Veteres) Compendium usque defixas, Contemplationes, nugis meis tam diu interpellare ausus sim: Teque e●iam, utut in hac re sim importunus, facile tamen posse exorari, ut amare pergas  
Virtutibus Tuis addictissimum Gualtrum Charletonum. Londini, 12. junij M. DC. LVIII.  
Postscriptum.  
ESt & aliud adhuc, quod ab. E. V. summoperè rogare velim; nimirum, ut, sicubi à verô aberravero, in viam reducere dignetur; nec Censoriâ, ubicunque videbitur, virgulâ abstineat. Mihi siquidem, exilitatis meae semper conscio, volupe admodum est, à Tali Viro corrigi, docerique,— Unum Tritonia Pallas Quem docuit, multâque insignem reddidit Arte.   

Galen, in 2. de Motu Musculor. cap. 5.  
QUi evidentibus fidem abrogat, sensûs est expers; qui verò de dubiis promptè pronunciat, temerarius est; qui autem, propter obscuritatem, quae in his inest, quae etiam clara sunt & manifesta, habet suspecta; de numero eorum est, qui dubitationibus oblectantur. Porrò, qui non modò quae suspecta habet; verùm etiam quae clara sunt, propter obscuritatem dubiorum, studet evertere; extremè fatuus est. Ne igitur sponte sensum nobis ipsi adimamus, neque dubitationis ●muli, aut fatui, aut aliud ejusmodi quidvis simus; sed quod tum rectum est, tum modestis Hominibus convenit; quod quid●m evidens est, promptè accipiamus; quod autem dubium est, per ocium quaeramus. ¶.   

Errors of the Press, Correct thus.  

PAge. 1. line. 20. read Plostique.  
page. 5. line. 1, read Aristoteleans.  
pag●. 8. line 2 read Void. and line 20. read 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉.  
page. 10. line. 7. read Homaeomerian.  
p. 13. l. 10. read ructus acidus, and l. 25 one and the same, etc.  
page. 15. line 9 read difficultly.  
page. 17. line. 13 read Pecquet.  
page. 26 line. 29. read Pecquet.  
page. 31. line. ult. read, other branches  
page 40. line. 4 read. it's own nature, etc.  
page. 61. line. 13. read, apposition.  
page. 64. line. 4. read, Venous.  
p. 72. l. 1. r. Slegelius, and the same, line. 12.  
page. 77. line. penult. read, only thus much.  
pag. 83. line. 18. read, draw themselves, etc.  
page. 86. line. 12. read Fracastorius.  
page. 89. line. 29. read lax.  
page. 95. line. 17. read voided.  
page. 114. line. 7. read Capsula.  
page. 116. line. 10. read Nerve.  
page. 157. line. 19 read Nerve.  
page. 190. line. 8. read, veins.  
page. 192. line. ult. read, covered.  
page. 193. line. 17. read Tailor's Mascle.    

OF NUTRITION. Exercitation the First.  
Of Nutrition.  
THe Platonist, 
Article  though He holds the Deity, and the world to be coeternal, 
Nutrition and Generation, one and the same Act of the soul or Formative virtue.  doth yet allow the World to have been created by God: and to solve the seeming contradiction, saith, that Priority was not [〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉] in respect of time, but [〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉] in respect of Nature; as the Sun and light are coevous, though the one be the Cause, the other the Effect. This, certainly, might be more justly said of the Generative & Nutritive Faculties (if at least, they be not one and the same); by one of which an Animal is produced, and by the other conserved. For, though the Formative Virtue may seem to precede in its operation; yet are the Stamina, or rudiments of the Embryo scarce delineated, or adumbrated, when the Nutritive gins to augment and perfect them: So as that it may rather be said to go hand in hand with the Plasticks faculty, than to follow after it; and what priority there seems to be in their operations, is rather in respect of Nature, than of time. To form, and nourish, are not only acts of one and the same soul; but so alike, that it is no easy matter to distinguish betwixt them. For, Generation and Accretion are not performed without Nutrition; nor Nutrition, or Augmentation, without Generation. To nourish, is to substitute such and so much of matter, as was decayed in the parts, namely flesh, nerves, veins, arteries, etc. And what is that in reality, but to generate flesh, nerves, veins, arteries, & c? In like manner, Accretion is not effected without Generation; for all natural bodies, upon the accession of new parts are augmented, and those new parts are such of which these bodies were first composed: and this is done, according to all the dimensions; so that, to speak properly, the parts of an Animal are increased, distinguished, and organised all at once. Farther, this is necessary both in respect of the Efficient cause, and of the Matter. The Former, because idem esse principium efficiens, 
As well in respect of the Matter, as of the Efficient.  nutriens, & conservans in singulis animalibus, necesse est; nisi aliam formam in puero, aliam in adolescente, et in seen aliam constituamus. The Latter, because all Animals (such as are produced per Epigenesin, of which is our discourse; not of such Infects, as are produced per Metamorphosin) are corporated of one part of the matter prepared by the Formative Spirit, and nourished and augmented by the rest. For, Nature doth nourish and amplify all parts of an Animal with the same matter, or humour (not with a divers) out of which she constituted or framed them at the first. Because, whatsoever is superadded to the parts, during their growth, aught to be of the same substance, with what was praeexistent, and so must consist ex congenere materiâ: their Renovation as well as first Corporation being effected by Epigenesis, Aggeneration, or superstruction. So that we may well conclude, that Nutrition is nothing else but continual Generation: and as necessary to the Conservation of every individual nature, as Generation itself is to the conservation of the Universe.  
To make this Necessity the more evident, we are to consider; 
The necessity of Nutrition, twofold, viz. Augmentation & Conservation.  (1) That forasmuch as an Animal cannot perform all the functions, of which its nature is capable, whilst it remains in the minute parts, and rude beginnings, in which it is first form; therefore, there must succeed a Nutrition, that may dilate and amplify those slender stamina, by interweaving and assimilating so many other congenerous parts, as serve to advance and augment the Animal to a convenient magnitude: (2) That since the chief principle of life in every Animal, is a certain indigenary Heat (analogous to pure flame, such as the most rectified Spirit of Wine yields, upon accension) which by continual motion and activity agitating the minute and exsoluble particles of the body, doth dissolve, and consume, or disperse them; of necessity, the whole Fabric would soon be destroyed, unless there were a continual renovation or reparation of those decays, by a substitution and assimilation of equivalent particles, in the room of those dispersed and absumed. So that, we see, the Necessity of Nutrition is Twofold; one in respect of Augmentation, the other in respect of Conservation.  
As to the continual Decay, or Depredation of the substance of our bodies, wherein the latter necessity of Nutrition doth consist; that we may the better understand the manner how it is effected, we are to inquire into the Causes thereof, viz. the Agent or Depredator, and the Matter or substance depredated.  
The Agent or Efficient Cause, with all Philosophers, 
The Efficient cause of the consumption of the parts, is the Vital Flame  we hold to be the Natural Heat, or Vital Flame, at first kindled, by the vegetative soul, or Plastic spirit, in the blood, constantly burning in the Heart, as in its fountain, or primary Focus, and thence by diffusion of itself through the arteries, warming, cherishing, and enlivening all parts of the body. This Lar familiaris is called 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, ingenitus ignis, by Hypocrates; 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, Accensio animae in cord, the Kindling of the soul in the heart, by Aristotle; and generally known by the name of Calidum innatum, the innate Heat. The principle of life, therefore, being a certain Fire, certain it is that the same cannot subsist or endure one moment of time, unless it be perpetually maintained or fed with some convenient 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, succendiculum, or Fewell; which is thereby indesinently consumed: for, all Fire whatever (that Elementary Fire, which the Aristotelians conceive to be so pure, as to need no pabulum or aliment, being a mere Chimaera) doth conserve itself only by the destruction of the matter, in which it is generated. So that, indeed, we have one and the same Cause both of our Life, and of our Death; or (to speak more properly) our Life is nothing but a continual Death, and we live because we die. For, so long we live, as this Vestall-Fire is kept glowing and shining in the sacrary of our heart: and when the same is put out, either by suffocation, or want of sustenance, life is instantly extinguished. And perhaps, it was to this Euripides alluded, when he said; 
Quis novit autem, an vivere hoc sit emori:  
An emori, hoc sit quod vocamus ●ivere?   
The Matter or substance consumed, we conceive to be the Fluid parts of the body, 
The Matter thereby consumed, not the substance of the solid parts, but the Fluid, and chiefly the Blood and Spirits.  especially the Blood and spirits, which having in them something of the nature of oil or sulphur, are the principal succendiculum, or Fuel of the vital Flame: and not the substance of the solid parts, at least not in that large quantity vulgarly supposed. For, experience teacheth, that sundry Animals, as Bears, Dormice, Swallows, etc. do sleep all the winter long, without receiving any supply of aliment: and yet have all their solid parts of their bodies, as large and firm, when they awake again in the spring, as when they first betook themselves to their dens or dormitories; nay, if we may credit Natural Historians, they grow fat in this time of their long abstinence. Which doubtless is to be ascribed to this, that the flame in their heart, all that time, being but gently moved, and burning quietly, doth consume very little of their spirits and blood. In like manner, we have examples of Leucophlegmatique virgins, who upon a decay of Appetite, have ●ndured long abstinence from all sorts of aliment: and yet have not been emaciated in any proportion to their so diuturn fasting. So that it is more than probable, that there is not so rapid and profuse an exhaustion of the substance of the solid parts, by the activity of the vital Heat, as Physicians have vulgarly imagined. In many diseases, we confess, the habit of the body is much extenuated; but that is only a subsidence or flaccidity of the Musculous flesh, caused by the defect of spirits and blood, by which the same was formerly distended and plumped up; not by any deperdition of the substance of the solid parts.  
Lastly, as for the Manner how the blood and spirits (and, 
The Manner how they are consumed, is by continual Dispersion.  if you please to have it so, also the less fixed and more easily exsoluble particles of the solid parts) are absumed by the vital Heat; it may be familiarly explicated by the example of the oil consumed by the flame of a Lamp. Flame (as reason defineth it) is a substance luminous and heating, consisting in a perpetual Fieri, i. e, an indesinent accension of the particles of its pabulum, or combustible matter, and perishing as fast as it is generated: so that fire is made fire, and again ceaseth to be fire, in every, the shortest moment of time; and when there remain no more particles in the 〈◊〉 matter, wherein i● m●y generate it self anew, it instantly perisheth. Continual Dispersion, therefore, being the proper effect of Fire; the matter or sewell, whereon it subsisteth, cannot but be in perpetual flux or decay. In like manner (that we may accommodate this to our present purpose) the Lamp of life consisting in a continual accension of vital spirits in the blood, as that passeth through the heart; those vital spirits, transmitted by the arteries to the habit of the body, no sooner arrive there, but as they warm and vivify the parts, so do they immediately fly away, and are dispersed into the air, carrying with them many aqueous parts, and (perhaps) some sulphureous exhalations. Moreover, there being in all parts of the body certain sweet and balsamical, or conserving spirits, as it were affixed unto and concorporated with them; the vital spirits meeting with and acting upon them, do by little and little render them volatile, and at length wholly disperse them: whereupon the minute particles, in which they did reside, become mortified, &, as excrements of the body, are ejected together with the exhalations of the blood. And this is (as we conceive) the reason and manner of the depredation made upon the parts, by the vital heat.  
If your Curiosity extend yet further, and you would inquire into the Quantity of Aliment daily devoured by this Biolychnium, 
And in what Quality.  or Lamp of life; the acute Sanctorius will tell you, that, according to his statique observations, men commonly avoid as much by insensible perspiration, in one day, as by stool, in fifteen. But so great is the variety among men, in respect of temperament, diet, age, exercise, the season of the year, and other circumstances; as that no definite compute can be made of this dispense. And yet we may be certain, that the proportion of blood and spirits daily exhausted by the flame burning within us, is very great: and that the most part of the matter of occult transpirations, is the vital spirits, which are continually generated, and continually dispersed.  
From the consideration of the Causes and Reason of the Deperdition of substance in Animals, we may opportunely progress to an enquiry into the Causes and Manner of the Renovation, or Restauration of it, by Nutrition.  
The Efficient principle (or 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, as Aristotle calls it) certainly, 
The Efficient Principle of the Renovation of the parts, what.  is the very same with the Generant, or Formative; because, as we said afore, Generation cannot be without Augmentation, and Augmentation is Nutrition. Not that we are of their judgement, who hold that Life and Nutrition are different, not in re, but only in ratione; for, the Embryo is nourished, before the Empsychosts: but that we conceive, that Life doth consist in a continual accension of vital spirits out of the blood, which is the pabulum of the Lamp of life; and that Nutrition doth consist in the restauration of what is consumed, by an Apposition and Assimilation of consimilar or congenerous matter.  
The Material, or Constitutive principle, we take to be a certain sweet, 
And what the Material.  mild and balfamical Liquor, analogous to the white of an egg, out of which the chicken is form. For since all Animals are nourished with the same, out of which they were at first fabricated, according to that common Axiom, iisdem nutrimur, ex quibus constamus; and that of Aristotle, eadem materia est, ex qua augetur animal, & ex qua constituitur primùm; and since they have their origine ex Colliquamento: we may well conclude, that the Succus Nutritius is in all qualities respondent to the Colliquamentum of the white of an Egg. Nor are they in the right, who think, that the parts of the body being divers, those of the Aliment ought also to be equally divers. As if Nutrition were nothing else but a selection and attraction of fit aliment; and that there were not required in every part a concoction, assimilation, apposition, and transmutation. For, the Aliment of all parts is common, and similary, such as the white of an egg; not heterogeneous and composed of divers parts: and it is the work of the Vegetative soul, as to form all parts out of one and the same homogeneous matter at first, so afterward to augment and repair them out of the like, by transforming that into the substance of each part, which is potentially all parts, and actually none. As from the same rain all sorts of plants receive their increment; because the water, which was potentially life to them all, is now made actually life to each, being transmuted into the substance of each. Whereunto the Philosopher had respect, when, opposing the opinion of Anaxagoras,  Principium rerum qui dixit Homaeomesiam, 
He saith; 
De gen. Animal. l. 2. c. 4.  Distinctio partiam non, ut quidam opinantur, propterea fit, quia simile suapte natura ad simile fertur: nam praeter alias multas, quas ratio ista habet difficultates, accidet, ut quaevis pars similaris se●rsim creetur Verbi gratia, ●ssa per se, & nervi, & carnes; si quis eam causum approbet, etc.  
Lastly, as to the Manner how the parts are refected, 
And the Manner how they are renorated.  or instaurated; it is most probable the same is effected by apposition, agglutination, and assimilation or transmutation; all which must in order succeed each other, before the act of Nutrition can be complete. For, the succus nutritius, being first prepared in the stomach and other organs thereunto inservient, must be brought and opposed to all the parts, that are to be nourished; then from contiguity by apposition it must be advanced to continuity, by agglutination; and lastly made of the same substance with them, by assimilation or transmutation, which is the perfection or ultimate term of Nutrition.  
From what hath been said, it easily appears, that the expense of the Aliment (at least of the Chyle extracted from it) is T●●fold; 
Consectary, of the twofold Expense of the Chyle.  one part thereof, being converted into the succus nutritius, for the instauration of parts: the other being converted into Blood, both for the fuel of the vital flame, and for the confection of Spirits. That we may, therefore, the better understand the process of Nature in both these Operations; it is fit, we inquire into the method of Chylification first, and afterward into that of Sanguisication: that we may comprehend the whole history of Nutrition from the beginning to the end.   

OF CHYLIFICATION. Exercitation the Second.  
Of Chylification.  
WHen we eat, 
Article  whatsoever of solid Aliment is detruded into the Ventricle or stomach (for Deglutition is by way of detrusion) doth for a while observe the same order, in which it was swallowed down; 
The Order of the Meat in the stomach.  what was first taken, lying undermost, and what last, uppermost: unless it chance, through intemperance, that an excessive quantity of drink so distend the stomach, as that the meat be set afloat; and then that order is changed into confusion.  
When our hunger is satisfied, and repast finished, 
The Posture of the stomach, in Concoction.  the stomach doth dilate itself more or less, according to the proportion of meat and drink received, so as to embrace the same closely and strictly on all sides; and then shut both its upper and lower orifice; the upper, that vapours may not ascend to the brain, and that the concoction may be the more perfect; the lower, lest any of the meat should descend into the guts, before it be converted into perfect chyle. Yet the lower seems not so strongly contracted, as the upper; because it hath been observed, that upon even a gentle compression of the body of the stomach, it easily yields to the pressure of the yet half-concocted meat, and permits it to pass into the guts. And sometimes the stomach is so weakened, by surfeits and frequent distension, as that neither of its orifices is drawn together so closely, as it ought to be; and in such case the Concoction is always imperfect.  
The meat thus received into, and embraced by the stomach, 
The Dissolution of the Meat, by an Acid humour found in ●he stomach.  is by and by moistened and diluted, partly by the drink, partly by a certain Acid humour contained in the stomach. Which being endowed with an incisive, penetrating, and dissolving faculty, doth as it were cut, and dissolve the solid meat into very small pieces, and (like an excellent menstruum) extract all the laudable and alimentary parts of it, ad modum Tincturae. But whether this Acid juice be ingenite in the stomach itself, or sent thither either from the Spleen (as hath been vulgarly believed) or from the caeliacal arteries (as is most probable) we shall hereafter professedly inquire. In the mean while, certain it is, that this Acid liquor (or spirit, as some have named it) is so necessary to the stomuch, as that it cannot happily perform its Office of Chylification without it. For (to omit how much the same conduceth to excitement of Appetite) when it is wanting, the concoction is rendered so imperfect, as that the meat is avoided whole, as it was swallowed down; which Hypocrates seems to intimate, in the 1 Aphor. 3. sect. where he saith, In longis intestinorum laevitatibus, si tactus acidus fiat, qui priùs non erat, signum bonum est. Certain it is also, that this Acidity, as it is not excited but by a moderate heat, so it is discussed and destroyed by an excessive. Which is the reason, why the appetite is weak and languid in phlegmatic constitutions, and cold distempers of the stomach; and in Fevers, and hot distempers, wholly taken away. Like as bread is very hardly leavened, in a cold place, and in an Oven not at all. But, we return from our digression.  
The mixture of the solid and liquid parts of the aliment, being by this time advanced usque ad minima, 
Which causeth a certain Fermentation of the Chyle therein.  so as the whole appears to be, one and the same fluid substance; in the next place succeeds a Fermentation, not unlike the motion arising in wine, while it defaecates itself. Which Fermentation we understand to be a certain Heat and agitation of all parts of the liquor, arising from a contest or strife betwixt the Spirits and crasser parts, while the Spirits endeavour to expand themselves, and fly away, and the gross parts oppose and hinder that their endeavour. Now this is that motion, which being equivalent to long Elixation, doth so fully impraegnate the potulent part of the Aliment, with the spirits and virtues of the solid, as that it puts on the form of a whitish juice, in colour and consistence not much unlike the Cream of barley, generally called the Chyle, as the function or action of the stomach, by which it is so confected, is called Chylification.  
But, here we are to advertise, 
All parts of the Aliment, not Chilified at once, but successively: and the first Chylified, first discharged into the Guts.  that all the meat doth not receive this commutation equally soon; it having been observed in dissections, that some parts have been perfectly converted into chyle, and that chyle detruded into the intestines and milky-veins; while the rest have remained wholly crude. Nor is it reasonable, that the whole mass of Chyle should be detained in the stomach; or that what is already concocted, should there stay and expect the perfection of what is not concocted: but that as fast as the chyle is made, so fast should it be discharged out of the stomach.  
We are to advertise also, that as to the Time wherein the work of Chylification is wholly confummated, 
The Time required to perfect Chylification, various, according to divers respects.  there is no small variety; as well in respect of men's individual temperaments, as of quantity and quality of meats they eat, and also of the time of their meals, with other circumstances. For, in some men the digestion is completed in 3, 4. or 5. hours' space; while in others it extends to 8. 10. nay 13. which certainly is to be ascribed chief to the abundance of heat and Acidity in the stomaches of Those, and to the decay of them in These. Again, by how much the greater quantity of meat is devoured, by so much the slower is it digested. The same likewise may be said of the quality thereof; because the gro●●er, tougher and harder the aliment is, by so much the more difficulty is it comminished, cut, dissolved, and fermented; and consequently the longer before it be concocted. Moreover, concoction is performed in the day much sooner, than in the night; notwithstanding the vulgar opinion, of the recession of the natural heat towards the stomach, in sleep, for the promotion of Chylification: because in the day, by reason of motion and exercise, the Circulation is more free and swift, and so the distribution of the Chyle more expedite. Lastly, Mastication of the meat in the month is so necessarily praecedaneous to concoction; as that by how much the smaller the morsels are, and the better chewed, by so much the sooner are they digested. Nay, among the parts of the same meat, there is no lesse-variety; so that some parts of bread and flesh commonly remain unaltered, a good while after others more tender and exsoluble are transformed into perfect chyle, and protruded into the guts. So that no certain time can be assigned to Concoction in all men. But Nature itself hath given us a sign, by which every single person may know, when this chylification is finished in his stomach; and that is a sense of emptiness, and appetite to a supply or recruit of Aliment.   

THE JOURNEY OF THE CHYLE Exercitation the Third. 
Article   
THe Chyle, being, 
The traduction of the Chyle, from the stomach and intestines, into the common Receptacle, through the venae Lacteae.  according to the manner declared, perfectly concocted, is by degrees (the stomach gently and gradually contracting itself▪) expressed or detruded into the Guts; and not attracted by them, as hath been commonly taught. The Guts being filled with this liquor, and by a certain peristaltique motion, or undulation, like that of worms creeping, contracting themselves successively from the first to the last; transmit the same downward. And as it passeth through them, there is a separation made of the profitable or alimentary part, from the unprofitable or excrementitious: the latter to be excluded by stool; the former to be protruded into the Venae Lacteae, or milky veins. Which opening themselves by small orifices or inletts, in infinite number, into the coats of the intestines; and running in continued channels from thence into the Mesentery: carry the Chyle into a certain common Receptacle or Gulf (called Receptaculum Pecqueti, from the inventor) consisting of a membranous substance, situate at the root of the mesentery, upon the vertebrae lumborum, and filling the space betwixt the Muscles Psoae. From this common Receptacle there are drived other ductus chyliferi, which running upwards, near the spin of the back, through the Thorax, and propagated quite home to the subclavian branches of the vena Cava, near the external jugular veins, exonerate themselves into them; so as the Chyle being there commixed with the blood, is by the ascendent trunk of the vena Cava, soon imported, together with its new associate, the blood, into the right ventricle of the heart. And this, according to the late invention of Perquet, and anatomical experiments of the most accurate Dissectors since, is the true Traduction of the Chyle from the ventricle to the heart: at least of so much of it, as is to be converted into blood, for the fuel of the vital Flame, and confection of vital spirits.  
That we may, with the more exactness and certainty, 
Of which there are two kinds, one arising from the Intestines; the other from the Glandules, in the Abdomen, into which the former sort exonerate themselves.  trace the footsteps of the Chyle in all its progress through these various and obscure Meanders; we are to observe, from anatomical Demonstrations, two things concerning the Chyliferous Conduits. First, that there are (besides the Common Receptacle, and channels from thence ascending to the chest and subclavian veins) two kinds or sorts of the venae Lacteae; one arising in slender capillary roots from the Intestines themselves, and thence delated through the Mesentery to some glandule or other, situate either in the Mesentery itself, or not far from it in some other part of the Abdomen, and there disseminated into capillary surcles: the other taking its origine out of that very Glandule, into which the former sort exonerate themselves. Secondly, that the Glandules in the Abdomen are not seated in the same places in all men; but are variously posited, here in some there in others, according as Nature (sometimes affecting variety in the same species, where conveniency admits thereof) pleaseth to fix them; and this without incommodity to the body: and that from the incertainty of the position of these Glandules, the Distribution of the venae Lacteae comes to be also various and incertain. For, Anatomy sensibly attesteth, that all the small surcles of the venae Lacteae of the former sort (arising from the intestines) do constantly tend to some one Glandule in the lower belly; and are distributed into the same, before they arrive at the Common Receptacle, or disembogue themselves into any vein; yea (as was newly said) that they produce another race of Capillary branches in the Glandules, in which themselves were terminated; and that many of those small rivulets concurring and uniting, make one greater channel, before they lose themselves either in the Common ocean, or any branch of the vena Cava. Now, from the foresaid various position of the Glandules, it comes to pass, that the Distribution of the venae Lacteae into their substance, and their new propagation out of them again, are so uncertain, as that it hath given occasion to some Anatomists to suspect, that the venae Lacteae are disseminated into very many parts of the body; when, indeed, they only come near those parts, and then pass by them, without effusing any part of the Chyle into them.  
Now, from these observations, 
But none of either kind tend to the Liver.  it is very probable, that all the venae Lacteae (before the Chyle loseth its milky colour) do exonerate themselves either into the vena Cava, or some branches of it. And as for the Lacteae Thoracicae, our sense demonstrates, that they empty themselves into the subclavian or Axillary veins (branches of the Vena Cava); so that none disgorgeing their fraught or chyle into any branch of the vena Portae; it is most manifest, that no part of the Chyle is imported into the Liver (as was long believed and taught), there to be converted into blood; and consequently that the office of the Liver is not Sanguification.  
Whether any of the venae Lacteae are distributed into the Paps, and womb; 
That the Milk in the Paps is not made of Blood, but of mere Chyle brought thither by some peculiar vessels: because  in women; though highly probable, is yet in dispute: no Anatomist having hitherto been so happy in his searches, as to discover by what secret ways or passages they tend to either. We say, highly probable; for, according to that judicious saying of Hypocrates, Licetvisum oculorum effugiant, ea tamen mentis acie comprehendantur; though they have thus long concealed themselves from the eye of the body, yet are they obvious to the eye of the Mind: and the acuteness of our Reason may herein supply the dullness of our sense. Now, to evince the probability of this Opinion, let us consider the sundry and weighty Arguments, that seem to assure, that the Milk in the paps is not made of blood; but mere Chyle brought into them by some peculiar vessels. Which though a seeming Parergy, is yet fully pertinent in this place.  
First, there are no convenient ways or conduits, 
There are no convenient conduits, by which Blood can be brought into the paps, in sufficient quantity.  by which Blood may be, in a due quantity, imported into the Paps, there to be whitened into Milk. For (1) the Arteriae Thoracicae can adferre but a small tribute of blood into the treasury of the Paps; and what they bring in, is soon exhausted and carried off again by the veins; according to the apodictical doctrine of the Circulation of the blood. But, did the blood remain in them; yet would it hold no reasonable proportion to the large quantity of milk usually effused in a day (which in healthy Nurses commonly amounts to two pints). Because the Arteries disseminated into the Paps, are exceeding small, as our eyes witness, and Vesalius, 
Examine observat. Fallop. pag. 89.  long since well observed, where He saith, Exiguae out ferè nullae arteriae adeunt mammas, quoth in mammarum cancro affectarum ablatione constat, ubi paucae aut ferè nullae arteriae sanguinem fundunt, cùm tamen venarum magna copia sit. (2) The Arteriae Hypogastricae cannot be thought to convey blood into the Paps; because they are terminated in a part far distant from their confines, and empty themselves where their streams are soon swallowed up and returned into the vena Cava by the Hypogastrick veins. (3) The same may be said of the Epigastrick arteries and veins. So that in respect of ways importing blood into the Paps, it appears altogether unlikely, that that should be the matter of Milk.  
Secondly, Blood is not a fit, 
Blood is nor a fit, nor possible Matter, for the generation of Milk.  nay not a possible matter for the generation of Milk. For (1) if blood should be imported into the paps, in sufficient quantity, and there extravasated; certainly it would be converted rather into pus, than into milk, as is frequently observed in Inflammations and Apostems of the Paps. (2) To what end should nature convert blood into milk, when that milk is to be soon converted again into blood, in the infant sucking it? (3) How is it possible, that the Chyle, which loseth its whiteness and other qualities, when it is transformed into blood; should resume them again, as soon as it becomes milk; a privatione ad habitum, is repugnant to Nature? (4) Meat and drink cannot be suddenly changed into blood, and that blood changed into milk; but experience teacheth, that the paps of nurses are filled soon after their repasts, and many women feel their milk flow swiftly into their breasts, almost as soon as they have drunk. (5) Women that are somewhat fat, have greater plenty of milk, than such as are lean: but, if blood were the matter of milk, the lean would afford more milk, than the fat; because the lean have larger arteries and veins, and so more store of blood. (6) If blood were the matter of milk, than would the bodies of Nurse's fall into dangerous sicknesses, from excess of blood, soon after they cease to give suck; because being long accustomed to the generation of so profuse a quantity of blood, for the supply of their milk; and that daily evacuation thereof ceasing, the whole body must needs be oppressed with that redundancy: but, they seldom complain of any Plethora; therefore etc. (7) If blood, not chyle, were the matter of milk, than were it impossible the milk should retain the odour and qualities of the meats eaten; since no manifest quality of the meat can be deprehended in the blood, much less in what is generated of blood, as being one remove further from it: but the Milk doth frequently retain the odour and other qualities of the meat and drink; Ergo. This is attested by the experience of Physicians, who give purging medicaments to Nurses, 
Comment in lib. Hippocr. de nat. pueri.  when there is cause to purge their children. Prosper Martianus, the best Commentator upon Hypocrates, hath an observation of a woman, who having taken a purge, soon after gave her child suck, and thereby endangered the child's life, a superpurgation ensuing in the child, while herself felt no effect of the medicament at all. No obscure argument, that the Milk deriveth its purgative faculty from the Chyle, not from the blood; for it were to be carried so long a journey, as through the heart and arteries, and therein undergo so many and great changes: doubtless the virtue of the medicine would be much weakened and dulled; nor could it be derived into the paps▪ so soon after it was first received into the stomach. Here may we seasonably recite that saying of Aristotle, 
7. De hist. Animal. cap. 11.  Si lactans pilum cum cibo aut potu angerat, ad memmas pervenit, & in earum papillis consistens, morbum inducit, qui 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 nominatur: and that rare observation also cited by Martianm, 
Loco eitat.  of a piece of a root of Cichory eaten in salad by a nurse at night, and taken out at one of her nipples the next morning. But, above all, this Experiment is most convincing. Let a nurse drink a good draught of milk tincted with Saffron; and within an hour or two after express the milk out of either of her paps, into a glass or other small vessel: and that milk shall have the odour, sapour, yea and the very colour also of Saffron. (8) Nor is the Milk made of the Menstruous blood, as some Philosophers have dreamt; because many bruit Animals have milk, that never suffer the monthly flux; because most newborn infants have some milk in their paps, 
De gen. anim. exercit. 55.  as Dr. Harvey hath well remarked; and because even Men themselves have been found with good plenty of milk in theirs also. Schenchius affirms, that he knew one Laurentius Wolfius, who from his youth to the 50 year of his age, had abundance of milk flowing out of his duggs every day. The like is asserted of a certain Fleming, by Wallaeus; and of divers others by Cardan, by Benedictus, by Aquapendens and other credible Authors. Nay, Historians report, that in America there are whole nations, among whom the men generally abound with milk, and suckle their children.  
To which we may add, that many nurses have their Terms, while they give suck, and yet find no diminution of their milk, at those times, more than at others. So that we see, how unreasonable it is to conceive, that blood is the matter of Milk.  
Thirdly, Milk and Chyle seem to be one and the same thing; 
Milk and Chyle agree in all their manifest Qualities; and are reciprocally convetible.  as may appear both by their mutual agreement in all their qualities, and by their easy reciprocal convertibility. As for their resemblance in manifest qualities; (1) They both have a fatty substance: otherwise neither could be fit either to sustain the Lamp of lise, or to instaurate the parts; nor can the blood contain any such fatty substance in it, but what is derived from the Chyle. (2) As Milk doth consist of two parts, the serum and crassamentum; so likewise doth Chyle, whose serum is drained away by the kidneys, and crassament by the guts. (3) As Milk, if kept overlong, especially in a warm place, or corrupted by any Acid juice, doth turn sour; so also doth the Chyle, and in the stomach of Calves is found a certain sour serum, which housewives use for the coagulation of their Milk; in like manner the same is frequently generated in the stomaches of men, which being ejected by vomiting, sets the teeth on edge; having acquired that sourness either by corruption from excessive heat, or▪ by the admistion of a melancholy juice. (4) They are equally sweet in taste; which is the reason, why many brute Animals lick up the milky liquor flowing from the secundines, when they bring forth their young, which is indeed the nutriment of their young, while remaining in the womb. (5) They resemble each other in colour, being both white; as the sense testifieth. (6) They both contain certain small Fibers, that seem to be educed from the more viscous and glutinous parts of the aliment. And these, doubtless, are those Fibers, which sensibly uniting themselves in the superfice of blood let forth into a cold vessel, appear in form of a whitish film, or thin skin; long mistaken by Physicians for cold, viscid and phlegmatic matter commixed with the blood: and if the red parts of the blood be gently washed away from them, they become distinctly visible. And as for their reciprocal Convertibility; that is clearly proved by this, that Chyle is easily converted into milk, in the Nurse; and that milk again converted into Chyle in the stomach of the Infant that sucks it. Now these many resemblances considered, we may safely conclude, that they have much more of reason on their side, who conceive Milk to be nothing but mere Chyle brought from the stomach to the Paps, by peculiar passages; and therein promoted to somewhat more of perfection: than they, who think it to be made of blood whitened in the glandules of the paps.  
Having, with so great verisimilitude, 
That Chyle is imported also into the womb, in pregnant women.  brought Chyle from the stomach to the Paps, for the sustenance of the infant, after he is born; it remains now that we see, whether any portion thereof be deduced also to the womb, for his nourishment before he is born. First, therefore, let us seriously consider, what light hath been anciently given to this obscure disquisition, by that Genius of Nature, 
From the Authority of Hypocrates, &  Hypocrates; who hath sundry pregnant Texts to this purpose.  
Uterum foetu grandiorem (saith He) comprimere mulieris ventrem, 
lib. de Natur. pueri.  & quoth in cibo potuque est pinguissimum & candidum, magisque uteri calore dulcoratum, in mammas tendere, & in uteros quoque exiguam portionem per easdem venas deferri. In which words the reverend Author toucheth upon two things very considerable and pertinent. (1) That the fat, white, and sweet Chyle is carried up to the paps, by compression of the Venae Lacteae, and the common Receptacle of the Chyle; the swollen womb being incumbent upon them, and pressing the Chyle upwards. For, that Compression cannot be understood of the veins and arteries in the lower belly, as if they were thereby urged to disgorge their blood into the paps, for the generation of milk; because, a compression of those veins and arteries, that are near the Vertebrae Lumborum, would necessarily hinder the course and recourse of the blood, requisite to the work supposed. But, as Perquet will have the weight of the Liver, moved up and down in respiration, to conduce to the compression of the stomach, venae lacteae, and receptacle, from the upper part of the abdomen: So will Hypocrates have it, that, from the lower part, the compression of the woman's belly by the greatness and weight of the child, doth cause the Chylo to alter its course (his words, in another place, being, 
lib. de Mulier.  convertitur ad maemm●s, quod est dulcissimum ex humido) and flow upward to the paps. Thus the Scythians, as Herodotus reports, had a trick to blow up the wombs of their Mares, by certain sufflatoria o●sea, like pipes, to the end that their bellies being compressed by the swelling of their wombs, the greater abundance of Chyle might be protruded into their udders, and so their milk increased. (2) Since by reason of the same Compression, the passage of the Milk, by vessels tending from the paps to the womb, is not so open and free, as while the burden of the womb was less; thence it comes, that so small a quantity of the Chyle is imported into the womb, as will not suffice to the nourishment of the Foetus. Much Chyle, therefore, flowing to the paps from the Venae Lacteae, and the Common Receptacle; and some milk also reflowing from the womb to them, by reason of this Compression mentioned: it is no wonder, if the paps at that time swell above measure;  
A second memorable place of Hypocrates, 
libr. citat.  to this purpose, is that; Add mammas enim & uterum ejusmodi venulae, & consimiles, feruntur. Cumque ad uterum pervenerit, lactis formam habet, ●oque exiguo puer fruitur: mammae verò, ubi lac exceperint, attolluntur & implentur.  
A third, to the same effect, is this; Foetus quod in sanguine dulcissimum est, ad se trahit, simulque aliquantulâ lactis portione fruitur. Where He hinteth the true cause, why it is unwholesome and dangerous for Infants to suck women with child, viz. because the best of the milk is attracted by the Foetus, in the womb, and the worst is carried to the paps. Which He more expressly declares in these words, Dum mammae exsuguntur, venae quae ad eas tendunt ampliores redduntur, & ampliores effectae quod pingue est è ventre a●trahunt, & in mammas transmittunt: giving the reason, why the fat and richer parts of the milk do not ascend to the paps, till after the birth of the child, who by frequent sucking doth dilate and amplify the vessels (formerly too small) through which the milk is to pass from the womb to the paps, and so make them more capable of the thicker liquor; and hence, doubtless is it, that the milk in women's breasts is always much thinner and wheyish, while they are with child, than after their delivery.  
From Hypocrates the First, let us go to Hypocrates the Second, 
Of Dr. Harvey.  the immortal Dr. Harvey; who, by frequent dissections of pregnant and suckling Animals, discovered that there is Chyle or milk imported into the womb. For, describing the Cotyledones or Acetabula of the womb, 
Exercit. de Vteri membranis & humoribus.  He saith; Cavitates istae spongiae majoris loculamenta magnitudine non excedunt; inque singulas earum. totidem vasorum umbilicalium ramuli tenuissimi profundè penetrant: quip in iisdem alimentum foetui reconditur; non quidem sanguineum, sed mucosum, ovique albumen crassius planè referens. Unde etiam manifestum est, bisulcorum Animalium Foetus (ut & alios omnes) sanguine materno non all. And, in the subsequent paragraph, He adds, coarctatis hisce acetabulis, non sanguis, sed albugineus' liquor emanat; eodemque expresso, illa statim contracta, albidiora, & flaccida conspiciuntur; ac demum mammarum papillas, aut verrucas pensiles majores referunt: And a little after, Opinor, carunculas omnes (uberum modo) non sanguinem, sed succum albumini similem concoquere, eundemque foetui subministrare. Again, in another place, tracing the way of this milky juice more accurately, He saith; ab utero per cotyledones pertingit ad carunculas placentae; quas quidem si digitis compresseris, ex earum una aliqua (tanquam ex papilla) succi istius alibilis facilè cochlearis mensura emulgetur: idque nullo apparent sanguine, quem attractu etiam valido, numquam elicueris; quinetiam caruncula sic emulcta atque inanita, compressaespongiae instar contrahitur & flaccescit; plurimisque foraminibus pertusa cernitur. Adeò ut omnibus indiciis pateat, carunculas istas esse ubera uterina, sive albuminis nutritii conceptacula. And a little after, He expressly affirms, succumillum in Gravidis ante partum, in acetabulis conservari; post partum verò, ad mammas deferri. Than which nothing can be more plain, more positive.  
To the Authorities of these great men, let us add the consideration of that great Sympathy or consent betwixt the womb and paps, 
And from the sympathy betwixt the womb and the paps.  so frequently observed in women. Which Consent cannot be caused by nerves, nor by veins, nor by arteries, nor by similitude of substance, nor by contiguity of situation; and therefore most probably, by mediation of these presupposed Chyliferous vessels tending from the paps to the womb. (1) Not by Nerves; because the paps derive their nerves from the fourth intercostal pair, or the fifth pair of the thorax: and the womb is supplied with sense from the nerves of the o●sacrum, and also from the sixth conjugation of the brain. (2) Not by veins or arteries; because they are, both, destitute of sense, as Galen himself affirms. (3) Not by Similitude of substance; because the paps consist mostly of Glandules, and the body of the womb is membranous. (4) Not by Contiguous situation; because the paps and womb are far distant each from the other. It being, therefore, most certain, that all sympathy betwixt parts of the body, doth arise either ex Vasorum Communione, or ex operis societate, or both; and that betwixt the paps and womb there is no communion of vessels, unless it be of some chyliferous vessels derived from those to this; and that there is a society of office betwixt the paps and womb, both containing the Aliment of the child: it is highly consentaneous to truth that there are such vessels (though yet undiscovered) by which the Chyle is carried from the paps to the womb, while the infant remains therein, and back again from the womb to the paps, after he is born. This being granted, we may clearly understand the ways and manner of the ascent of the milk from the womb to the paps; and the reflux of it from the paps to the womb, so frequently mentioned by Hypocrates. We may understand also, how the good or evil affections of the womb are communicated to the paps; and how it comes, that a Cancer cured in the paps, doth revive and grow again in the womb, and vice versâ. And thus may we understand those Aphorisms of Hypocrates; Si gravidae mammae graciles fiunt, repent illa abortit; si gravidae lac multum è mammis efflu●t, foetum imbec●llum significat; si solidae mammae, foetum saniorem. In respect of these vessels, are we moreover to interpret that Rectitude of consent betwixt the paps and womb, intimated in that Aphor. Gravida gemellos gerens, si dextera mamma fiat gracilis, marem; si verò sinistra foeminam abortit: foetus enim mares in dextris, foeminae in sinistris magis.  
To conclude this Disquisition, therefore, 
A conjectural description of the Chyliferous vessels tendin from the paps, to the womb.  since it is manifest that there are some such Chyliferous vessels, or ductus, by which the paps and womb have a reciprocal commerce; it is not improbable, they are derived from the extremities of the Chyliferous veins of the thorax, where those enter into the subclavian veins, or the branches of the vena cava; being disseminated on each side one, to each pap●; whereunto so soon as they have insinuated themselves, and dispersed several small surcles, to lead a long the chyle to the nipples, they may be conceived to emit others branches downward along the abdomen, that insert themselves into the womb, on each side one; and perchance some one also into the bladder, it having been observed, that Chyle hath been avoided by urine. But, what need we thus anticipate, by conjecture, when we daily expect the discovery of the ways through which they pass, by Anatomists, who now a days exercise themselves in strict enquiry after them?   

OF SANGVIFICATION. Exercitation the Fourth.  
Of Sanguification.  
FRom the smaller and less conspicuous Rivulets of the Chyle, 
Article  we now come to survey the grand and plainly visible Current thereof; 
The most part of the Chyle is converted into blood.  which being imported (as we formerly declared) into the subclavian veins, from them into the vena cava, and thence immediately disembogued into the right ventricle of the heart, is therein converted into a liquor of a different colour and nature, viz. Blood, for the fuel of the vital Lamp, and the continual refection of spirits vital. And here we are (for method's sake) in order to consider (1) The Mutation which the Chyle arriving at the heart, doth therein suffer, or the Action its self, called Sanguification; (2) The Agent, or principal Efficient of that Mutation; (3) The Manner how it is effected; (4) The Uses of the Blood, after it is made; (5) The Motion of the same, in order to those uses.  
Concerning the FIRST, viz. the Action of Sanguification; 
Not by an Organical, but a Similary Action.  we advertise, that it is not an Organical action, or such as depends upon the peculiar constitution, or fabric of any Organical part of the body; but merely a Similary one. For, since the blood, when made, is a similar body; and the Chyle of which it is made, is likewise a similar body; and that the Chyle doth not become blood, by separation of any one or more parts of it, from any other (as the Urine and Bile are made) but only by a kind of Exaltation of it nature, or an advance of those Natural spirits it containeth, into vital or more sublimed and active ones, while the vital spirits, preaexistent in the Ventricles of the heart, do enkindle the same hea●, and cause the same diffusive or expansive motion in the Natural, which themselves have formerly acquired: we say, considering these things, it is manifest, that the work is done by simple Assimilation; and consequently that Sanguification is an Action similar, not Organical, as hath been long erroneously affirmed.  
Concerning the SECOND, viz. the Efficient, let us first examine what that cannot be; and so we shall the more easily and certainly find what it must be. The prime Agent, or Author of the work of Sanguification, is not either the Liver, as Galen and his Sectators conceived and taught; or the veins, as some Anatomists have dreamt; or the substance of the Heart, as Aristotle and his Disciples have asserted; or any other organ of the body.  
To be more particular; we affirm, the Liver not to be the Agent in the work of Sanguification; 
Whose Primary Efficient, is not the Liver;  and that for sundry reasons. (1) No part of the Chyle is brought to the Liver, by any one or more of the Venae Lacteae: they in the lower belly generally exonerating themselves into the Common Receptacle; and those in the Thorax being terminated in the subclavian veins: and therefore it is impossible the Liver should transform chyle into blood, when no chyle can arrive thereat. (2) There is blood to be seen in an Embryo, before even the very rudiments of the Liver are delineated; and what hath being before, cannot be the effect of what hath no being till afterward. That the blood hath priority of existence, is manifest from the observations of Dr. Harvey, 
de gen. Animal. exercit. 18.  who expressly affirms, Sanguinem dari, antequam quicquam corporis reliqui existat; esseque eum, prae coeteris omnibus foetûs par●ibus, primogenitum; & ab ipso, tum materiam, ex qua corporatur foetus, tum nutrimentum, quo augetur, procedere; esse denique (si modo ulla fuerit) primam particulam genitalem. (3) After the Chick is perfectly form in the egg, and hath its veins and arteries replenished with blood; yet doth the Liver still remain pale and whitish, not without some small tincture of yellow, which observation doth of itself alone demonstratively depose the Liver from the office of Sanguification, and confer that dignity upon some other Agent. For, how can the Liver, supposing the Chyle were brought to it, give a deep redness thereunto, while itself yet continueth white? Can any thing give that to another, which itself hath not? This also is certified by the experience of Dr. Harvey, who thereupon firmly concludes; jecur & calorem, 
exercit. de gen Animal. 51 sub finem.  & colorem suum à sanguine mutuatur; non autem sanguis à jecore. From hence it may be observed, that the native colour of the Liver is not red, but pale, with a faint mixture of yellow; and that, what redness it doth afterward acquire, is communicated to it from the blood continually percolated through the parenchymas of it. Both which may more plainly appear by this, that in a Chick not yet excluded from the shell, that yellow paleness of the Liver is visible, even the very last day of the Hen's incubation; though at that time the same gins to incline toward some degree of redness, which is more and more augmented every day after the chick is hatched. Again, if you fill a bladder with warm water, and through a slender pipe inject the same, by the trunk either of the vena Cava, or vena Portae, into the Liver; and so rinse out the blood remaining in the vessels and substance thereof; you shall sensibly perceive the redness of the Liver to vanish away, and a certain duskish or sooty yellowness succeed in the room. Which obscure yellowness, doubtless, hath its original merely from the tincture of Choler. However, most certain it is, that the Liver hath natively no redness at all; and what it afterward contracteth, is adventitious, and from the blood. To this purpose is that easy experiment of Dr. Harvey; 
〈◊〉 jam citato.  imò verò jecur, lien, renes, pulmo, & cor ipsum (si sanguinem inde omnem expresseris, cujus praecipuè gratia viscera dicuntur) expall scunt illicò, & partibus frigidis accensenda sunt. So that we may with good warrant conclude, that the office of Sanguification was, by the Galenists, assigned to the Liver, rather upon inconsiderate partiality, than any right at all.  
(2) Of the veins also the same may be said. For, 
Nor the veins.  if that rule of Galen holds true (as certainly it doth); Quod mutatur, in ejus speciem, à quo mutatur, facessit; the veins can never be thought fit, to transform the Chyle into blood. For, their Colour is white and somewhat translucid; their substance viscid, membranous, and bloodless; they have no parenchymas, and very little either of heat or spirits of their own: whereas, on the contrary, the Blood is of a deep red, not translucid, of a substance fluid and interminate, and abounds with heat and spirits. And, therefore, it were vain to expect an Assimilation, where the supposed Agent and Patient are of natures in all things so incompatible, so contrary. We deny not, that the veins in some respect conduce to the Conservation of the blood; but how? Only as they are Organs, inservient to the defence of it from external injuries, and the reduction of it from the parts upon which it was newly affused out of the arteries. And as for any similar Action of the veins upon the blood; they have none at all: yea, their office of Conserving it doth consist chief in their inactivity, i.e. in this, that they are not apt to alter or deprave it; as Glass-vessells are the best to conserve liquors in, because they neither communicate any ill qualities of their own, nor permit the like to be communicated from others to them. But, that which doth principally conserve the blood in the purity of its nature, is the very same thing that makes it from the beginning, viz. the vital Heat and Spirits derived from the Heart, which by their enlivening warmth, and continual motion, do not only vindicate the blood from corruption, but also all the solid parts of the body, and so even the veins themselves also, as long as the Lamp of life continueth burning. And that being once extinguished; how soon, alas! do all parts of the body yield to the quick tyranny of corruption?  
(3) Nor hath the Heart more right to this noble office of Sanguification. For, 
Nor the Heart: but the vital spirit, residing in the blood.  that borrows all its vital heat and activity merely from the vital blood contained in its ventricles, and distributed into its substance by the Coronary arteries. Of which vital influx were the Heart deprived, but for some few moments; it would soon become as torpid and motionless, as any other part of the whole body; so far is it from exalting the Chyle into so noble a Nectar, as the blood is, by any similar action of its own. To assure this, please you, take out the yet-panting Heart of any the strongest and soundest Animal, and having with warm water rinsed all the blood out of the ventricles, fill them again with warm Chyle or Milk; and see whether it will be able to convert the same into blood. Certainly, you shall find none the least change to be wrought upon the liquor infused. Yet the Heart is a solid and strong part; and one would scarce think it probable, that that action, which it is supposed to perform, by reason of its solid substance, should be intercepted in so short a space of time. Forasmuch, therefore, as the Heart doth, in a moment's time, surcease its activity, and desist from the work of changing Chyle into blood, as soon as the vital blood is effused out of its ventricles; it is as manifest, as certain, that the virtue Generative of blood, is not radicated in the solid substance of the Heart, primarily, but in something else, viz. in that very thing, upon whose absence immediately that virtue is destroyed, which is the vital Blood. Again, the dissection of Living Animals teacheth us, that the vital Heat is much greater in the ventricles, than in the substance of the Heart: and Reason biddeth us thence to infer, that the same Heat is originally in the ventricles, and but at second hand, or by way of communication, in the parenchyma. Now, if the Activity of even the Heart itself, be derived originally from the vital Blood; and that the vital Blood be more powerful than the Heart: we can hardly deny the same to be the Primary Cause, or Agent of Sanguification; unless (at least) it shall appear, that the vital blood is less apt for such a work, than the Heart. But, comparing the agreeableness of the Heart to such an office, with that of the vital Blood to the same; we shall quickly perceive which of the two hath the greater. For, the vital Blood is of the same species with the thing to be made or produced; but the substance of the Heart is far different from it. It being, therefore, canonical, that all Natural Agents endeavour, according to their energy, to assimilate to their own nature the thing, upon which they act: it seems of equal certainty, that the activity of the vital Blood, is most properly consigned to the work of Sanguification. A further evidence of this, may be drawn from hence, that the Chyle and Blood are most intimately mixed together in the ventricles of the Heart; while the Chyle doth only superficially and in transitu touch the side of them. To which may be added, that the Chyle makes but a very short stay in the Heart: but remains constantly commixed with the Blood, until it be thereto perfectly assimilated. Lastly, the blood flowing in the heart, arteries, and veins, doth exceed the Chyle of one meal, in quantity at least ten times, and in strength or activity, an hundred; (for, what is more potent, than that spirit, which enliveneth the whole body; what softer, gentler, and more easily superable, than Chyle?) and therefore, no doubt but the Blood doth easily obtain the victory over the Chyle, and overrun it with his own nature.  
To secure this Assertion from all doubt whatever, let us have recourse to the observations of Dr. HARVEY (the true Oedipus in all abstrusities of this kind) of the progress of Nature in the generation of the parts of an Animal successively one after another; 
which alone formeth the blood in a chicken, out of the Colliqua mentum.  and we shall soon be satisfied, that the First Blood is made by the vital spirit. That great man attesteth, that the white of the Egg doth for some days after the Hen hath sat a-brood upon it, retain its native whiteness, and that out of the Colliquament, or White, made more thin and fluid, the Chick is generated, without the addition of any other matter. The Question than is only this, How that white colour in the Colliquamentum, or so much of it as the Plastic faculty converts into blood; comes to be changed into red?  
Certain it is, this cannot be effected by any thing that was read before; because there is no part of the Egg of, or inclining to, that colour; and the yelk remains entire a good while after there is blood to be seen in the punctum saliens. Nor is it the Fleshy parts, that communicate this vermilion tincture to the blood, because they remain white after the blood is made out of the Colliquamentum: and it is much more reasonable, that the fleshy parts derive their redness wholly from the blood, perpetually irrigating and washing them in its Circulation. For, their redness grows upon them by degrees, and that sooner or later, according to the degrees of Heat impressed upon the Egg by the Hen, and according to the greater or less quantity of blood arriving at them. Some parts, which are but lightly touched by the blood, never become red; in which account are the coats of the Eyes, the Ligaments, Tendons, Membranes, Bones, etc. Others obtain a certain paleness dashed with a sparing mixture of red; as the Glandules which as they are furnished with greater or smaller arteries (respective to their magnitude) so are they tinged with more or less of redness. The Musculous flesh is more deeply died with scarlet, than the Glandules; as being irrigated with greater streams of blood. The Kidneys, Liver, Spleen, Lungs, and Heart, are all washed with full streams of blood; and therefore have a deeper die of redness, than any other parts: and yet are much less red, than the blood itself. Now it is more reasonable to conceive, that the Greater should communicate its virtue to the Lesser, than on the contrary, the Lesser to the Greater. For, how can any Natural Agent operate beyond the sphere of its activity, i.e. the measure of its power? or communicate that to another, which itself wanteth? Again, nothing can have an activity, before it hath a being▪ and consequently the solid parts cannot give a redness to the blood, because they are not in being, till after the blood. Nothing, therefore, remains to be the Efficient of the Blood, but the Vital Spirit, kindled originally in the purest part of the seminal matter, or Colliquamentum which we may well denominate the Vital Liquor.  
Concerning the THIRD considerable, viz. the Manner of this grand operation of the Vital Spirit; 
The Manner how blood is first generated in an Embryo, by that Vital Spirit.  though it be very obscure, yet do we not think it altogether inexplicable, if we deduce the blood from its first Origine, the newly mentioned Vital Liquor. This Vital Liquor, before it assumes the colour and form of Blood, doth begin to separate itself from the other parts of the Egg (to which it is at first promiscuously admixed) and to run its self out into certain slender rivulets, or branchings, which afterward become Veins. These rivulets concurring in a point, meet altogether at the centre of the Colliquamentum; which centre being the principal seat of the Plastic spirit, and acquiring a certain mication, or pulsation, is then called Punctum Saliens? And all this is done, before there is any the least appearance of blood in the Egg. So soon, therefore, as these Rivulets are conjoined, the Flux of the Vital Liquor is, for some time, so hindered by, and repressed in them, as that being indesinently agitated by the Spirit of Life, it aestuateth, and endeavours to expand itself and enlarge its bounds: and seeing that it cannot flow back again toward the circumference, by the same passages, which brought it toward the centre, by reason of fresh supplies of Vital Liquor pressing it forward continually in the course begun; it is compelled to force itself again into the seminal matter, from whence at first it began its motion, through other slender conduits newly for that purpose form, and then it gins to flow in a round. For, this appears to be the true reason of the Circumgyration of the Vital Liquor, from the very beginning. Soon after this, the Rivulets or pipes first made, and leading from the circumference to the Centre, become Veins; and the others made in the second place, and leading from the centre to the cicumference, become Arteries: which yet others disallow, in respect of the fabric of the valves) and then in the point of their concourse or confluence, the Heart is framed. Through which Heart, and the conduits annexed or (rather) continued unto it, the one sort tending toward, the other from ward the centre; the Vital Liquor doth (while life lasteth) perpetuate its motion: and at the same time irrigate and vivify all parts of the matter, which it continually washeth in that its circular course. Now this Circula●ion is begun, for some time before the Vital Liquor is excocted into blood; as may be conceived from hence, that when the motion of the Punctum Saliens is plainly visible, there is no blood, but only a clear, transparent liquor, or (as the Learned Harvey calls it) the Colliquamentum: and also from hence, that while the Seminal Matter is yet thin and fluid, the Vital Liquor can easily disperse its channels through the same; there being then no impediment to that its expansive motion, and operation: but, if it should defer its dispersion and making of rivulets, till after the solid parts were made; 'tis hard to conceive, how it could be able to shoot itself forth into branches, and make its way through them.  
This Dance of Life being thus begun, 
and in what part of the Conception it is first generated, viz in the Chorion.  though no Blood yet appears, yet soon after it doth appear; the Vital Liquor, while continually (though slowly) circulated, by little and little assuming the form of Blood. And the place in which the blood first shows itself, is the Chorion; not the Heart. For, seeing that the Chorion ought to be made solid and firm, before any other of the parts of the Conception, insomuch as it serveth as well for the safeguard, as nourishment of all the other parts; and that to this end, there is no moisture coming from without, that might hinder its being made solid; and that the Chorion, as involving the whole conception, is the first part that receiveth the warmth of the Hen, during her incubation: we say, from hence it comes, that the vital Liquor doth first of all obtain the form of Blood in the Chorion. And this is effected the sooner, because the vital Liquor doth more easily emit its exhalations, in that place, as being in the circumference, than in any other more remote from it: and unless those exhalations were freely emitted, the Spirits of the Vital Liquor would inevitably be soon extinguished. It is moreover probable, that at this time, the Vital Heat is more potent and active in the exterior parts of the Conception, than in the Centre; and so, that the First Blood is made in the Chorion, where it first discovers itself to the sight of the inspector. Hence also we may observe, that because there is no blood to be discerned in the Punctum Saliens, for many hours together after blood is discernible in the Chorion: therefore, must the Circulation of the blood be exceeding slow in the beginning; for, as soon as the blood, that is in the Chorion, performing its circular motion, arriveth at the Heart, it cannot but be discerned in the Punctum Saliens.  
Now, 
In the generation of Blood, what are the Concurrent Extrinsecal Causes: and what the Accessary Organical.  these observations being undeniable, we may safely assert; that the Vital Spirit in the Seminal matter, being excited and assisted by the external heat of the Hen sitting upon the Egg; and by degrees becoming active, and infusing heat into the vital Liquor, wherein it doth reside: doth thereupon, in process of time, induce the colour of blood; and that only by means of its vital Heat and Motion; and that no other part is to be reputed for Principal Agent, in the work of Sanguification. Nevertheless, we do not hereby exclude Concurrent extrinsical Agents, or Causes: but into that account readily admit the Hen, whose warmth at first both excited and assisted the Vital Spirit in the work of Sanguification; and the substance of the Heart itself, which afterward conduceth in some sort to the same. Nor do we repudiate Accessary Organical Causes; as the Fabric of the Heart, the Arteries and Veins, all which are inservient to the continual motion of the blood. Only we affirm, that the Vital spirit, by reason of its Heat and Motion, hath a just right to the dignity of Principal Agent, in making of Blood.  
We say, 
The Conversion of the Colliquamen●um into Blood, by the heat and motion of the Vital Spirit; illustrated by sundry analogous' Experiments, and Observations.  By reason of its Heat and motion. For, that Colours frequently are advanced from a white, or pale, to several kinds of Red, merely by Heat and Motion; is demonstrable by sundry easy and familiar Experiments. Our Confectioners well know, that long boiling of Quinces and other Fruits doth give them a ruddy colour. So likewise Fruits baked in an oven, are more inclined to redness, than while they were raw. The same is true also even of Flesh, and Bread, which by baking or roasting, acquire redness in their superficial parts: and some Chemists affirm, that a Tincture of Bread will assume a certain degree of redness, after long digestion. This is not, we acknowledge, common to all Liquors, especially simple ones; for simple waters, and such as are destilled, suffer little or no change of colour, upon decoction, though long. But generally all Compound Liquors, especially if they contain any Nutritive juice, in competent quantity, and have besides any touch of salt, or Acid spirits in them: are observed to acquire a sanguine tincture, by decoction. Upon which fertile hint, as we conjecture, that highly Learned, Industrious, 
in Apolog. pro circulatione sanguinis, advers. Parisan. p. 119.  and Acute Person, Dr. ENT, seems to have grounded that ingenious opinion of his; that the Redness of the Blood ariseth ex Aciditate spiritus vitalis salinei, from the Acidity of the vital spirits, having their original from a certain seminal salt. However, we have good reason to persuade ourselves, that all vital Liquors, i. e, such wherein the vital spirits of Animals do reside, are apt to acquire more or less of redness; provided they obtain sufficient Heat, and agitation or strife in their motions. This is evident in all Sanguineous Animals, in which the Chyle is first white, and after changeth into blood. And as for Exsanguious Animals, they also give some testimony of this truth; as may be instanced in Oysters, in which blood is frequently found (and yet without a prodigy) in summ●r time, by reason their vital Heat seems then to be augmented: and in winter, when their Heat is again lessened, below what is requisite to induce redness, their vital juice is always whitish. To return to sanguineous Animals; as they are generally hotter of constitution, than Exsanguious; so are their Sanguine parts always hotter, than their pale and white parts. In like manner, in cold diseases, as the Green sickness, Cachexy, Dropsy, and in all Phlegmatic constitutions, the blood is paler, than in hot diseases and constitutions. Again, the venal blood, as it loseth the heat, which it had acquired in passing through the heart and arteries; so doth it proportionately by little and little lose that florid and deep scarlet dye, that it had in the heart and arteries. For, blood let forth of a vein, appears bluish, and comes short of that lively fresh scarlet, that is observed in blood effluxed from an Artery. All which clearly show, by whose efficiency it is, that the vital juice (in Sanguineous Animals) is excocted into Blood; and what conserveses the same in its primitive purity and lustre: viz. the vital spirit continually renewed in, and enlivening the blood; for, that being once extinguished, how soon doth the blood degenerate into Cruor, and lose its fresh scarlet tincture?  
Having thus investigated what that is, 
That the same Agent, which maketh the first blood in an Embryo, doth make it ever after in an Animal, d●ring life.  which makes the First Blood in an Embryo, by converting the vital Liquor, from a white, into a purple Nectar: we cannot be long in exploring what that is, which in Animals maketh blood all the life after, by converting the Chyle likewise, from a white into a red liquor. It is an infallible rule, you know, that the identity of Effects dependeth upon the identity of Causes; because an effect is not supposed to be, until it hath obtained existence from its proper causes: and at the same time the causes give that existence, they cannot but give also the identity belonging to it. All which is imported in that common Axiom, Idem, quà idem, semper facit idem. For, though Free and Arbitrary Causes may act at liberty, and, by varying the manner of their operating, vary also their effects: yet Natural ones are bound up to a determinate mode of energy, and must, as long as they continue the same, act after one and the same way, and so produce invariably the same effects. Forasmuch, therefore, as the Efficient of the First Blood, is an Agent Natural, and not Arbitrary; if it continue the same in an Animal, while the Animal lives, it must of necessity continue the same operation. That it doth continue the very same, during life, is most certain; because it is the Principle of life, nor can life subsist for so much as one moment without it. Nor doth this Efficient of Blood only persist the same in the body, that it was at the first conception; but grows every day more vigorous, potent and fit for the work, until the Animal hath attained to the flower of his age: and to imagine that an Agent Natural (such as the Vital Spirit) should at any time become idle, intermit its operation, and not exercise all its forces; is grossly absurd. Conclude we therefore, that the Vital Spirit, as it is the Efficient Cause of Sanguification, in the Embryo from the first Conception; so is it constantly Author of the same work, until the Animal dieth.   

OF THE USES OF THE BLOOD. Exercitation the Fifth.  
IT followeth now, 
Article. 1.  that we inquire, To what End Nature hath consigned so continual a province, 
That the Blood is not the General Nourishment of the body. Because  as this of Sanguification, to that subtle Agent, the Vital Spirit; or, more plainly, of what Use the Blood is, in Sanguineous Animals. Concerning this, there are (for aught we know) but Two opinions extant; the One, that the Blood is the general Nutriment of the body, or Matter by which the substance of the parts is daily instaurated; the Other, that it serveth both for the maintenance of the vital Flame, which cannot subsist without a perpetual supply of convenient fuel; and for the refection of vital spirits. The Former, though very ancient, and generally embraced; yet (in our judgement) deserveth to give place to the Latter: because though the Latter be new, and as it were of but yesterday standing, yet it hath much more of probability, as may be evinced by these ensuing Arguments.  
(1) It is well known, 
The contrary opinion is subject to sundry both inexplicable difficulties, and irreconcilable incongruities.  that Aristotle, in many places of his works, hath earnestly contended, Sanguinem esse ultimum totius corporis alimentum, that the blood is the ultimate, or most perfect Aliment of the whole body: and that the whole School of Physicians hath given its suffrage to verify that his Tenent. And yet many things, not easy to be explicated, and less easy to be reconciled one to another, may be observed to attend thereupon. For, Physicians, when, in their Physiological discourses, they treat of the nature of the Blood and endeavour to make good, that it serveth to no other use, but only to afford Nutriment to the body; they suppose it to be a substance, not simple and homogeneous, but mixed and compounded of Four several juices, promiscuously flowing together in the same streams: deducing their principal argument hereof, from the Combinations of the Four First Elementary Qualities (as they call them) and accordingly teaching, that the ingredients of blood are the two sorts of Bile, or Choler (viz. the yellow, and the blackish) Phlegm, and Blood properly so called. Further, of each of these different humours, They make some Nutritive (as assuming the whole body to be made up of them) others Excrementitious: and then They decree, that the blood doth consist of those divers Nutritious humours, as of Heterogeneous parts. After, though they allow the Phlegm to be the colder and cruder part, and so capable of conversion into good and laudable blood, by more intense heat, and longer concoction; and likewise allow the Choler to be convertible into Melancholy, by adustion; and blood to be convertible into both choler and melancholy, by the same means: yet will they by no means admit of a regression of either Choler or Melancholy into blood. Now, if these things be true (as may well be doubted) and that there is no possible regress of Melancholy into Choler, nor of Choler into laudable Blood: then will it inevitably follow, that all the other three juices are but only in Order to Melancholy: and that Melancholy is the principal and most perfectly concocted Aliment. Nay more, They must grant two sorts of Blood; the one, the whole mass of blood contained in the veins, and composed of those four humours: The other, the more pure, more florid, and more spiritual part thereof, which in a stricter sense they call blood, and which some will have to be contained only in the heart and arteries, apart from the venous blood, as deputed to peculiar and more noble Uses. Now, according to this distinction, it is manifest, that not the pure arterial blood is the nourishment of the body, but the base, composed of divers juices, or rather chief the Melancholy; to which as to their ultimate term▪ or perfection the three others tend. And how incongruous it is, to conceive, that the body is nourished, either with impure juices, or with Melancholy a cold dry and earthly humour as they define it: is obvious to men of even the shallowest understandings.  
(2) If the Blood were the Universal Aliment of the body, 
There are sundry parts, into who●e substance the blood is not admitted.  then certainly no part could be nourished, at which the blood doth not arrive: but we see that many parts are nourished, as the Brain, Bones, Nerves, Ligaments, Testicles, etc. to which notwithstanding the blood is not so brought, as to be admitted into their substance: and therefore the blood is not the Universal Nourishment. We ●ay, so as to be admitted into their very substance; for though blood be found in those parts, yet doth it not penetrate deeply into them, as the Nutritive juice ought to do: 
lib. de Alimento.  alimenti enim vis (saith Hypocrates) ad ossa usque pervenit, & ossium parts. The blood doth, indeed, touch upon those parts, in its running round the body; and but only touch them; and for this reason, that all the parts may be cherished and enlivened by the Vital Spirits, which it carrieth along with it. Thus, in the Brain, veins are not where found, but disseminated upon the Membranes, that are their support; the Plexus Choroides and some other few places excepted. Which perhaps is the reason, 
1 Hist. an. c. 16.  why Aristotle denied any blood to be contained in the brain; because it is not effused into the substance thereof, as it is into the fleshy or musculous parts.  
(3) Men that are fat and plump, 
Fat men generally have the least blood, and Lean the most.  have but little blood; and such as are spare and lean, have abundance: which could not be, if blood were matter of nourishment. And because Lean persons have much blood; therefore are they more lively, courageous, and active, as abounding with Spirits, in proportion to their great quantity of blood. Hence is it also, that Lean persons bear large evacuation of blood, without detriment of health; because their fleshy and musculous parts, as being firm and solid, drink up the least quantity of blood in their pores, and so there remains the more for the fuel of the Vital Lamp. Whereas, on the contrary, gross and fat persons, suffer great damage by large effusion of blood; because the habit of their bodies being despoiled of Spirits and hotter blood, is filled with serous humours, and so easily degenerateth into a Cachexy. In like manner, in a gross body, where are more parts to be nourished, there ought to be the more blood to nourish them: but gross men, for the most part, eat much less, than lean; because they have less veins, and being inclined to sedentary and unactive lives, they consume but few Spirits. For it is but a small portion of the Chyle, that is, converted into the Succus Nutritius (the dissipation of the substance of the parts, being neither so sudden, nor great, as hath been vulgarly conceived, as we formerly explicated) and the rest, after its unprofitable parts are separated, being brought to the heart, is mostly consumed in Spirits. Such things, therefore, as relieve the Spirits, suddenly satisfy our hunger; as good wine. 
2 Sect. Aph. 36.  Whence that Aphorism of Hypocrates; Famem, vini potio solvit: because wine revives the Spirits.  
(4) In Animals dying of famine, and men dying of Consumptions; 
Men perishing by famine, have their arteries and veins full of blood.  good store of blood hath been found in the veins and arteries. Which were impossible if blood were the nourishment of the body: for, than no Animal could perish by famine, while it had any blood in its vessels: nor could the body be so emaciated, in consumptions, while the veins contain so plentiful a source for the resarcition of the parts. Which reason, among others, induced Dr. Harvey, 
de gener. Animal exercit. 52.  to conclude; etsi sanguis sit pars corporis, non tamen huic nutriendo solum destinatur▪ Enimvero, si huic duntaxat usui inserviret, nemo fame periret, quamdiu sanguinis quicquam in venis reliquum habetur: quemadmodum & lucernae flammula non extinguitur, quamdiu inflammabilis olei in eâ vel minimum suppetit.  
(5) If the blood were changed into Ros & Cambium, as they call them; 
The blood continueth red and florid, in the habit of the body.  then, certainly, in the habit of the body, and capillary veins, it would appear white, or inclining to whiteness: but our sense assureth, that it is no less red and florid in those places, than in the central parts of the body.  
(6) Hypocrates hath a singular observation, 
libr. 5. Epid●m. ●. 25.  of a certain man, a patiented of his, who being much emaciated, and every day more and more consuming, 
Hypocrates cured a man of extreme Leanness, only by profuse Phlebotomy.  notwithstanding the most restorative aliment he could take; was at length cured, only by a very profuse eduction of blood out of the veins of each arm, after all other means had been in vain attempted. Which would not have happened, if the blood were the nutriment of the parts. The reason of this admirable cure seems to be this. There is (as we have more than once declared) a twofold expense of the Chyle: one part goes to the instauration of the parts, as being, or constituting the Succus Nutritius; the other supplies the Vital Spirits, under the form of blood. Now when one of these exceeds, the other languishes; and the too plentiful exhaustion of the Chyle, upon the blood being the cause of this man's Leanness, his recovery succeeded upon a turning of the stream of the Chyle upon the parts for their sufficient Nutritive juice.  
(7) If the blood did nourish; then would Fat, 
The blood is observed to be less unctuous and glutinous, in the Arteries, that carry it to the parts; than in the veins, that return it from them.  unctuous, and glutinous blood be most accommodate to that use: for, the serum hinders the apposition of the blood, and therefore Ichorous and weeping Ulcers are seldom consolidated. Now, the blood is observed to be more unctuous and glutinous in the veins, than in the arteries, in which it is commonly more diluted, and full of serum: but the blood is carried to the habit of the body by the arteries, and from thence brought back again by the veins. Which, certainly, is a very weighty argument, against the Blood's being the nourishment.  
(8) Betwixt the thing nourished, and its nutriment, 
There is a manifest Dissimilitude betwixt the blood, and sundry parts of the body.  there ought to be a certain Analogy, or similitude; according to that old saying, Parts quaslibet alimento ipsis maximè consimili enutriri: but betwixt the blood and several parts of the body, instead of this requisite resemblance or affinity of qualities, there is in many things a perfect Dissimilitude or disparity. For, if we compare the blood, with the brain, the Horny coat, or Humours of the Eyes, the Bones, tendons, and other the like parts, we shall find little or no proportion, or resemblance betwixt them. In an Appolexy, where the brain is overflowed with blood effused into the substance of it, all the ideas or marks of things formerly known, are quite obliterated, nor doth any perception of them remain. Likewise when the eye is bloud-shodden, the perspicuity of the coats of the eye is changed into opacity, and the transmission of the visible species through them hindered. The bones also are so many ways discrepant from the blood, that it seems impossible they should be constituted thereof. And of the tendons, Nervs, membranes, etc. the same may be said.  
(9) The Manner of Nutrition, is a certain promotion of the aliment from the state of crudity; 
The progress of Nutrition, is from crudity, to fusion and volatility; not retrograde from volatility to fixation: and so the Aliment ought to be more crude, or fixed, than the parts to be nourished.  to the state of concoction, or an Exaltation of its Spirits to a further degree of activity. And therefore, the aliment must of necessity be more crude, than the part therewith nourished. For, that promotion is not by any degradation, or Fixation of the Spirits of the aliment; but by an Exaltation or reduction of them nearer to volatility. Forasmuch therefore, as the Spirits already in the blood, are approached or advanced nearer to the state of volatility, than those contained in the parts above mentioned: certainly, the blood cannot be thought a convenient nourishment for them. The redintegration of those parts ought to be expected from such nutriment, as is more fixed than themselves are: Otherwise how could it suffice to the solidation or firmation of them▪ But, the blood is of a more rough and grating nature, and its spirits more advanced toward volatility, than those residing in the solid parts: and in that respect is wholly unfit to nourish them. Moreover, it is necessary, the Nutritive juice should be sequestered from the blood, before it can be opportunely brought and apponed to the parts: if so, to what end was it admixed to the blood at all? shall we believe, that Nature (rather than seem idle) doth make any thing, only that she may unmake it again afterward?  
(10) What is itself nourished, cannot (without absurdity) be thought to be the nourishment of another: 
The blood is itself nourished, and doth consume the substance of the solid parts: and so cannot be their nourishment.  nor can that which is the cause of the exhaustion of the solid parts, be the matter of their redintegration. That the blood is itself nourished, is manifest from the large access of Chyle to it, after every meal: and that it is the cause of the exhaustion of the solid parts, is also manifest from hence, that the Vital Heat, whose subjectum inhaesionis is the blood, is the only consumer or depredator of the solid substance of the body. For, whatever be the effects of the Vital Heat, residing in the blood, as its proper and original subject; the very same may be justly imputed also to the Blood itself. For, albeit we sometimes ascribe the actions of things to their Qualities, or Faculties; thereby indicating the Formal Reason, or Manner; by which the substance operateth: yet we cannot deny, but it is the very substance itself, to which those Qualities are inherent, that really performeth the action. It is the blood itself, therefore, which by reason of its inherent Heat, doth uncessantly pray upon the substance of the solid parts, and causeth them to make provision for their reparation, even after they have attained to their perfect magnitude. Nor doth it only so, but it moreover, in case of famine, converts the solid substance of the parts into its own, supplying its defects out of their decays. This is manifest, in long abstinence from meat, when though the habit of the body be extenuated, yet (provided the person take water, or some other thin liquor, that may be a vehicle of the Humours) do the arteries and veins continue full of blood. Thus also in Fevers, though the stomach be so weak, as to abhor all things but small beer, or cooling Juleps; yet doth the blood all that while repair itself, by colliquating the substance of the solid parts, and converting it into its own. For, how otherwise could the streams of blood be daily replenished? And, that they are replenished, is evident from hence, that though the quantity of blood be diminished (proportionately to the strength of the patiented) by Phlebotomy, in the beginning of the Fever: yet will it be again, in a day or two after, so increased, as to require a second, and perhaps a third diminution; and that, notwithstanding the sick person hath received little or no nourishment all that while. An undeniable argument, that the blood, in that defect of supplies from the Chyle, doth repair itself out of the spoils of the solid parts. Now, since the blood doth exhausted and depredate the solid parts; how can it consist with reason, that it should be their nourishment?  
(11) The Aliment of the parts ought to be in all things like that matter, of which they were at first composed. 
The First Matter, of which the parts are made, is not Blood; but a certain liquid juice, very like the white of an Egg.  For, what is superadded to the parts, as they are augmented, is of similar substance with that, which was preaexistent in them, and so of necessity must be constituted ex congenere ma●eria. Now, the Materia prima of all the parts, is not blood, but a certain liquid juice, perfectly resembling the White of an Egg, of which the Chicken is form; only with this difference, that in viviparous Animals that Liquor is more thin, and like the Colliquamentum in Eggs, after the Hen hath fitten upon them some days. For even Viviparous Animals conceive a kind of Egg in their wombs, which is involved in a thin membrane, and containeth a certain viscid humour, very like the White of Eggs, attenuated and melted by the warmth of the Hen's incubation. And this Liquor is the very matter of which the Embryo is first form: but very unlike the blood, in substance, colour, and all other qualities. As therefore the parts are not made up of blood, at first; so are they not augmented or nourished by it afterward.  
We said, That the blood is not the General Nutriment of all the body; 
Nevertheless the blood may be the Nourishment of such parts, whose substance is mostly sanguineous: and what those are.  thereby admitting, that it may be the Particular nutriment of some parts. For, as to the Parenchymata Sanguinea, the parts whose substance is chief Sanguineous; forasmuch as they seem to consist mostly of the thicker parts of blood coagulated in them, and affixed to their vessels and fibers; and that they have no Nervs derived unto them, through which the Succus Nutritius might be imported into them: we conceive, that the decay of their sanguineous particles, is daily repaired by the fresh opposition and affixation of the like particles of the blood. And in this account, we reckon the Liver, Spleen, Kidneys, Heart, Lungs, and red parts of the Muscles. Yet in all these, whatsoever of Fibers, Membranes, or Vessels, is found commixed with their Parenchyma or Sanguineous substance; all that is to be excluded from the capacity of being nourished by the blood. But, as for all the Fibrous, Membranous, and Nervous parts of the body, and all the Parenchymata Sanguinea, as the Brain, Spinal Marrow, the Humours of the Eyes, Teeth, Bones, and Glandules; it is most probable (from the reasons alleged) that they are nourished, not by the blood, but by some sweeter, softer, and milder liquor, congenerous to the spermatick matter, or Colliquamentum, of which they are originally constituted; which is daily brought and effused or instilled into their substance, out of the Nervs inserted into them. But of this distribution of the Succus Nutritius, by the Nervs, we shall have opportunity to discourse more particularly hereafter.  
Well then, of what Use is the blood? 
The manner, how the Vital Heat is conserved; and the Vital Spirits continually recruited, ex sanguine.  Why truly (according to the latter opinion recited) we conceive it to serve both as the Pabulum, or Fuel of the Vital Flame, and as the Matter of which the Spirits Vital are confected. Concerning the manner, how Flame is maintained by its Fuel; we have already plainly, though succinctly, discoursed. And, as for the Manner how the Vital Spirits are continually recruited, ex Sanguine; we may understand it to be thus. The Spirits, contained in our solid aliment, being at their first admission into the stomach, crude or in the state of Fixation; are soon after, partly by admistion of Liquids', and partly by Fermentation, promoted, from the state of Fixation, to that of Fusion. In this state, the richer or more nutritive parts of the solid aliment, being, by way of Liquation, throughly commixed with the drink; there resulteth a certain milky juice, called the Chyle; which is a Liquor abounding with sweet, mild and delicate Spirits. Now these Spirits, so soon as they are brought to the Heart, and there commixed with the Vital blood; are by little and little exalted to a third state, viz. that of Volatility; and so become fit subjects to entertain the Vital Heat, and want only another recourse to the heart, to be therein, as it were by accension, advanced to the height and dignity of perfect vital Spirits. For, the Vital Spirits● differ from the Spirits contained in our aliment, no otherwise than in the gradual preparations and exaltations now mentioned. We are to advertise moreover, that the Heart, in its Systole, is not contracted so closely or straight, as to expel all the blood contained in its Ventricles, at once: but leaves a good part thereof remaining in them, after the contraction is ended. And that this remaining blood doth heat and kindle the portion of blood next effused out of the veins into those ventricles; and by that means exalt it to the condition of Vital blood. We further observe, that in the Spirits of the blood, there are sundry degrees of volatility; so that some attain to the highest degree of volatility much sooner, than others; and none, until they have undergone several Circulations, and as many fresh Accensions in the Heart. For, in every Circulation they grow more and more subtle and agile; and so must at length be brought to the requisite height of volatility. To which having once attained, in the very next Circulation (though they are restrained and kept in, by the sides of the heart, and coats of the arteries, while they remain therein) being diffused upon the outward parts of the body, as they warm and vivify those parts, so do they soon fly away, and disperse themselves into air. And while these thus fly away, other Spirits less volatile are, by the colder temperament of the parts, by which they pass, somewhat repressed: so that the force of their expansive motion is much abated, the Mication or panting of the blood interrupted, and the blood wherein they are, of Arterial, or vital blood, is made venouse or Natural; and such it continueth, until the next circulation bring it again to the heart, there to be kindled afresh, and exalted to the due heat of vitality. Which once acquired, it recovers its intermitted motion of Mication, or rising and falling alternately, and yields a fresh supply of spirits vital; which being transmitted to the habit of the body, are soon dispersed, like the former.  
And thus is the vital Flame kept alive, at no less expense, 
The Reason of the Mication, or panting motion of the Blood, in the arteries.  than a continual dissipation of the most votatile spirits of the blood. For, that vital Heat ariseth from within, and the most subtle spirits are the first Movers to the excitement thereof: the motion by which they do it, being their endeavour to expand themselves, and to dilate their bounds, while the other grosser elements, or ingredients of the blood, oppose them therein. And this strife, or Counter-activity of the spirits, on one part, and of the grosser ingredients of the blood, on the other, doth exhibit the general Essence of Heat. To which may be added this short observation, that in this Contention, one while the spirits prevailing, do lift up, or swell the mass of blood; another while the grosser elements (the contraction of the Heart and arteries assisting them) prevailing, countermand and interrupt that expansive motion: and that by this alternate conquest of these Antagonists, is made the Mication or Rising and Falling of the blood, the one in the Dilatation, the other in the Contraction of the Heart and arteries. Forasmuch, therefore, as the vital Heat doth consist in the rarefactive motion of the spirits, and the renitence of the grosser parts of the blood; and that the spirits, for the most part, at least alternately, obtain the victory and dominion over their opponents: it seems most consentaneous to truth, that this vital Heat cannot be preserved, without a perpetual expense of the most pure, i.e. the most volatile spirits of the blood; and consequently necessary, that during life, fresh spirits must be perpetually minted out of the blood, to defray that vast and continual expense. And this we conceive to be the true progress of Nature, from the first reception of the spirits contained in the Aliment, to their education into the Chyle, their sublimation in the heart, their gradual exaltation to the highest degree of volatility, and lastly their dissipation through the skin into aer: upon which depends the Conservation of the vital Heat, and the continual Generation of the vital Spirits.   

OF THE MOTION OF THE BLOOD; ITS CONDITIONS AND CAUSES. Exercitation the Sixth.  
Of the Motion of the Blood, its Conditions and Causes.  
NAture (which in all her works, hath the End, 
The Method of the Chapter.  and Means conducing to that End, always closely connected in one idea) having ordained the perpetual generation of this vital Nectar, the Blood, in Animals, for the Uses, in the precedent Chapter recited: that she might not be deficient in the means requisite to fulfil those Uses, hath also ordained, that the blood should be carried from the Fountain to all the parts, in living streams, by a certain admirable Motion, necessary to its distribution through the whole body. Now, that we may fully understand the nature of this Motion, we are to consider (1) the Manner; (2) the Conditions; (3) the Causes of it.  
Concerning the FIRST; we observe, 
That the Motion of the blood is Circular;  that the blood is continually carried, or rather driven from its fountain, the Heart, in the centre of the body, by the Arteries, to the circumference; and back again from the circumference, to the centre, by the veins, irrigating, cherishing, and vivifying all the parts, as it passeth along: and that therefore, this Motion was, by the glorious Inventor of it, Dr. Harvey, called the Circulation of the blood; quòd, Ejus enim semper redeat labor actus in orbem.  
For, in the first place, 
From the Vena Cava, into the right Ventricle of the heart.  the blood is effused out of the vena Cava, into the right ventricle of the Heart; as may be evidently seen in living Animals dissected, especially in Coneys. For, if the trunk of the vena Cava be bound with a ligature, both above and below the heart; you may perceive all the blood contained in the space betwixt the ligatures, to be speedily discharged into the right ventricle of the heart, to which the vena Cava is conjoined.  
From the right ventricle of the heart, it is (the heart contracting itself) expelled into the vena arteriosa, 
From the right Ventricle, by the Vena arteriosa, into the Lungs:  and so into the Lungs; but not through the septum transversum, or middle partition of the heart, as some have imagined, conceiving the same to have some certain obscure passages from the right into the left ventricle; only because they could, without much violence, thrust a style, or probe through it: when, indeed, those passages are not made by Nature, but by the point of the probe; the flesh of the heart being so tender, as that it is easily penetrated, by any hard and pointed instrument though but gently intruded.  
Passing through the vena arteriosa into the very substance of the Lungs; the blood is immediately returned into the venosa arteria, 
From the Lungs, through the Arteria Venosa, into the left Ventricle:  and through that into the Left ventricle of the Heart. This is demonstrable thus, Having made a ligature upon the great branch of the Arteria venosa; near the pericardium, in the lungs of an Animal yet living; you may observe that branch to be soon filled and much distended with blood, in that part, which is toward the lungs, and that emptied and flaccid, that is next the heart: and upon remove of the ligature, the blood will flow amain from the lungs to the left ventricle. Now, there being no other way, by which this blood can flow to the left ventricle, but from the lungs: it must of necessity descend thence, by the Arteria venosa.  
The left ventricle having thus taken in a quantity of blood, answerable to its capacity; 
From the left ventricle, into the great Artery, and thence into the smaller Arteries.  the heart instantly contracting itself, expelleth the same (at least, good part thereof) into the Great Artery (arising from the left ventricle) thence into the lesser arteries, and so into the substance of the flesh; from whence the blood is intruded into the capillary veins, by them into the greater veins, from them into the vena Cava, and at length into the right ventricle of the heart, there to begin the same circular progress again.  
We say, from the capillary arteries into the substance of the Flesh. 
From the smallest Arteries, through the substance of the flesh, into the smallest veins.  For, as to those, who will have the blood to pass out of the small arteries, into the small veins, per anastomosis, by certain inosculations, or open passages from those into these: we challenge them to demonstrate to the sense, any such way of intercourse or communication betwixt arteries and veins, in the whole habit of the body; and Dr. Harvey did the same before us, when He said, De Anastomosi venarum & arteriarum, 
de mot. cord. & sang. cap. 9  ubi sit, & quomodo sit, & qua de caussa, neminem hactenus rectè quicquam dixisse, suspicari licet. And why may not the blood be as well conceived, to permeate through the pores of the flesh, as water through the pores of the earth, the sweat through the skin, the serum through the parenchymas of the Kidneys, or as the same blood through the thick substance of the Liver.  
Nor is only that blood brought back to the heart, by the vena Cava, 
How the New-made blood is circ●●lated with 〈◊〉 old.  which passed through it before; but the stream is augmented by the access of fresh Chyle also, imported into the subclavian branches of the same vena Cava, and thence into the right ventricle of the heart. For, this is not only easy to be done, in respect of the vicinity of the ascendent and descendent trunk of the vena cava, to the right ventricle: but also necessary, there being no other way for the new supply of blood to pass; and that it is done, this experiment doth testify. The vena cava being bound both above and below the heart; all the blood contained betwixt the two ligatures, will in a very short space be discharged into the right ventricle.  
Again, the Heart seems to immit more blood into the Great Artery, 
That more blood passeth through the heart, in an hour, than can be supplied from the chyle, in several days.  in the space of one hour, than the proportion of Chyle can amount to, in several days. For, in most men, the Heart makes more than 3000. pulses, in an hour; and at every systole it expels some blood out of its left ventricle into the Aorta; as may be sensibly demonstrated by this, that upon a ligation of the Aorta, near the heart, and an incision made betwixt the ligature and the heart, you may observe some quantity of blood (more or less) to be squirted forth by the incision, at every systole, unless the heart be grown weak and languid; and yet even in that case, some quantity of blood will issue forth at the hole, once in 3 or 4 pulses. Nay, when the cone or point of the heart is cut off, and the heart held upright; though the ventricles be not then full, yet will some blood be squeezed out of them, every time the heart contracts itself, 
2 cap. de. mat. cord. & sanguine.  and that to the distance of 3 or 4 feet, as Dr. Harvey observeth.  
As for the Quantity of blood admitted into the ventricles of the heart, when it is dilated, 
The Necessity of the Circulation inferred from three considerations, viz.  and expelled into the Great Artery, when it is again contracted; it cannot be precisely determined. For, if in the same individual person, the motion of the heart, being sometimes more strong and swift, and sometimes more weak and slow, doth make the Circulation of the blood more swift, or more slow proportionately: certainly in the species, it must be impossible to commensurate the quantity of blood passing through the heart, at every pulse; since there is great variety among men, in respect of their different temperaments, ages, sexes, diet, exercises, passions; and the like, all which vary the pulse, and consequently the motion of the blood. However, that some satisfaction may be given to enquirers herein, we are to consider Three things, viz. (1) How much blood may be contained in the heart of a Man, in its Diastole; (2) How much may be expelled out of it, in its Systole; (3) and How many Pulses, or Diastoles and Systoles, the heart doth commonly, in healthy and temperate men, make in an hour.  
Concerning the First; 
the quantity of blood contained in the heart, in its Diastole;  there are different observations. Harvey saith, that in a man's heart dilated, he found more than two ounces of blood. Plempius affirms, that he found almost two ounces. Riolan will allow scarce half an ounce, in the left ventricle; but somewhat more in the right. And Hogeland comes much lower, admitting only one dram. But, all men generally grant, that the whole mass of blood contained in the body, doth seldom exceed 24 pounds, or pints, and as seldom come short of 15.  
Concerning, 
the quantity expelled out of it, in its Systole.  the Second; we say, that in every systole is expelled either the fourth or fifth or sixth, or at least the eighth part of the blood received into the heart, at the precedent Diastole. Harvey supposeth at least one dram, and proves that his supposition from the sudden effusion of all the mass of blood, if but the least artery be cut: and because all the blood may be transmitted through the heart, in the space of half an hour, He thereupon concludes for certain, that much blood is expelled into the great Artery, at every systole. Conringius also makes the same compute. Walaeus and Sleyelius admit half an ounce: but compute only from one scruple. Hogeland acquiesceth in one dram. And Thom. Bartholinus brings it down to only half a scruple. But they all agree, that in the contraction of the heart, the sides of the ventricles are not drawn so close together, as to expel all the blood contained in them.  
Concerning the Third, 
The Number of Pulses, in the space of an hour.  we remember, that Primrose reckons 700. pulses in an hour; Riolan 2000; Waleus and Regius 3000. Cardan 4000; Plempius 4450; Sleyelius 4876; Bartholinus 4400, or thereabouts; and Harvey about 2000; each one numbering the pulses in his own wrist.  
Now, from these three things premised we may collect how much blood may be expelled out of the left ventricle of the heart, into the Aorta, in the space of one hour, according to the several numerations of pulses viz. From ℈ j 3000 times repeated there arise lb 10 ℥ 5 Of blood passing through the heart into the arteries, in one hour. ℈ j 4000 lb 13 ℥ 10 ʒ5 ℈ j ℈ j 4450 lb 15 ʒ3 ℈ j ℈ ss 4400 lb 7 ℥ 7 ʒ5 ℈ j ℈ j 2000 lb 20 ℥ 10 ℈ ij 2000 lb 41 ℥ 8 ℥ ss 2000 lb 83 ℥ 4 ℥ j 2000 lb 166 ℥ 8  
Again, setting it down for a ground, that the quantity of blood contained in the whole body, doth amount only to lb 15. (for that is according to the most modest account) and allowing some part thereof to be consumed by the Lamp of life, and as much to be supplied out of the Chyle: we may infer these 4 necessary Conclusions. 

(1) That more blood is transmitted through the heart, once in every hour, than can be supplied out of the Chyle, in many hours.  
(2) That all the blood in the body is transmitted through the heart, once in a quarter, or half, or a whole hour, or in two hours at most.  
(3) That so much is not required to the conservation of the vital Flame, and the confection of vital spirits.  
(4) That, since the vessels are not broken, that the blood cannot return back out of the heart, nor be any ways dissipated: it is absolutely necessary, that the blood must return to the heart again by the veins, or be Circulated perpetually, as the immortal Dr. Harvey hath demonstrated.    
Nor is this Circulation of the blood only Particular to some Arteries and Veins (as some have inconsiderately imagined) but Universal, or common to them all, 
That the Circulation is Universal, in all the Arteries and veins of the whole body.  throughout the whole body. For though it be, indeed, more demonstrable to the sense in the Limbs, where the vessels being ample and conspicuous, admit of ligatures more conveniently, than those in the Inwards: yet doth observation teach us, that the motion of the blood is the very same in the very entrails also. In particular (that we may deduce it through the most conspicuous Arteries and veins of other interior parts, beside those already mentioned) the blood is carried, in the 

Abdomen, to the 

Testicles, by the spermatick Arteries: from them, by the spermatick veins, into the left Emulgent and vena Cava.  
Intestines, by the Mesenterick Arteries: from them, by the Mesenterick veins, into the Ramus Mesentericus, and thence into the vena Portae.  
Spleen, by the left Celiacal Artery: from it, by the Ramus splenicus, into the vena Portae, and thence directly into the Liver.  
Stomach and Omentum, by other branches of the Celiacal Artery: from them, by the Gastrick and Epiploical veins, into the Ramus splenicus; thence into the vena Portae, and so to the Liver.  
Kidneys, by the Emulgent Arteries: from them, by the Emulgent veins, into the vena cava.  
Outside of the Heart, by the Coronary Artery: back again, by the Coronary vein, into the vena Cava.    
Thorax, to the 

Pleura, by the Intercostal Arteries: from it, by the veins thereof, into the vena Azygos, and thence into the vena Cava.  
Head to the Membranes of the Brain, by the Carotides and Neck-Arteries (which tend to the four Cells of the brain, but are not therein terminated, as some Anatomists have thought:) from them, by the jugular veins, into the ascendent trunk of the VENA CAVA.      
All which is discoverable to the sense, by binding those vessels, in Animals cut up alive. For, the swelling, caused in either vein or Artery, by the flux of blood there arrested, will always appear on that side the ligature, from whence the blood flows.  
Here we are to advertise, that in the Foetus, or Infant-unborn, the manner of the Circulation of the blood, 
But, after a peculiar manner in an Infant unborn.  through the vessels of the Heart, is different from that we have described. For the blood is not carried from the Mother's womb, into the Umbilical Arteries; but from the Placenta Uterina (in which those Arteries are terminated) into the Umbilical vein: which conducteth it along to the Liver of the Foetus, from whence it is transmitted by the Vena Cava into the right Ventricle of the heart. Being brought thither, it is transferred into the Vena Arteriosa: but, because the Lungs are not yet moved, as after the birth, in respiration; and so their vessels are not dilated and contracted alternately, and consequently they can neither receive the blood out of the Vena Arteriosa, not impel it into the Arteria Venosa: therefore hath the providence of Nature contrived and framed Two peculiar passages, the one a conduit or pipe, conveying the blood from the Vena Arteriosa, into the Great Artery; the other certain foramen, hole, or inlett, by which the blood passeth from the Vena Cava into the Arteria Venosa, thence into the left Ear of the heart, and so down into the left Ventricle. From thence (as well as that from the Vena Arteriosa) it is infused into the Great Artery. So that in an unborn Infant, Nature useth the two Ventricles of the heart, as if they were but one: and this, lest the infant should have his Blood too hot and adust, while he wants the ventilation of the air, and expulsion of fuliginous exhalations, through the Lungs. From the Great Artery, the blood is sent into the Umbilical Arteries, which return it to the Placenta Uterina; where permeating the substance thereof, it is again infused into the small branches or (rather) roots of the Umbilical vein, by them into the trunk, and at length into the Liver, Vena Cava, and Heart, as before.  
Having thus explained, by what ways the blood is moved in a round; 
This Motion of the blood, is  it follows, that we consider the CONDITIONS of that its motion. Concerning which, we observe that the Circulation of the blood is,  
(1) Continual. 
Continual;  For, since the Heart is continually in motion, and takes in blood, in its Diastole, and dischargeth the same again, in its Systole, never intermitting that its proper action, but in great swooning fits, or in the very article of death: it is necessary, that the motion of the blood be likewise continual.  
(2) Vehement; as may be inferred from the hardness and distension of an artery, 
vehement;  or vein bound with a ligature. For, nothing can be distended to great hardness, by a thin and liquid matter, especially upward, unless that matter be with vehemence impelled into, and retained in it. But, this vehemence of the motion is greatest near the heart, and is afterward diminished by degrees, according to the several degrees of distance from the heart; so that the extreme arteries have but little pulse, unless it happens, that the impellent force of the heart be increased, as in Fevers, Inflammations, Violent exercise, some passions, etc. Which is also the reason, why the veins have no pulse, the impulse of the blood being less in them, than in the smallest arteries.  
(3) Swift. 
swift;  For, an artery or vein being compressed by ligature, will swell up and be distended, as it were in a moment; and the blood may be observed to flow in its course very swiftly, so soon as the ligature is removed. But how swiftly, is not easily determined; there being so great variety of Causes, Natural, non-natural, and Preternatural, that accelerate or retard the flux of the blood: only thus may be inferred from the precedent compute of the number of Pulses, and the quantity of blood expelled out of the left ventricle of the heart, in every systole, That the whole mass of blood doth pass through the heart once in an hour or two, at most. Yet is not the current of blood near so swift in its channels, while they are whole, as when one of them (vein or artery) is cut: because in that case, the blood streams forth into the free and easily-yielding aer, without any resistance; but being confined in its vessels, it is forced to distend them, and drive-on the foregoing current.  
(4) As swift in the Veins, as in the Arteries. For, 
Of equal velocity in the Arteries and veins.  though the impulse be more vehement in the atteries, as being continued to the heart, than in the veins; and therefore it might seem reasonable, at first consideration, that the motion should be proportionately more swift in the arteries: yet, considering, that the Arteries are still smaller and smaller toward their extremities, & that the flux of the blood must needs be more and more retarded, as it approacheth those extremities; and on the contrary, that the veins grow wider and wider, from their extremities, to the centre of the body, and so the blood hath still larger and larger spaces to run through, in its return to the heart; we may safely conclude (conjecturally) that the velocity of the motion is as great in the veins, as in the arteries. This is also confirmed by sense; for, the Vena Cava, in all that tract from the Liver, to the subclavian division, may be observed to beat, as often as the Great Artery; and so must import blood into the right Ventricle, as fast as the Aorta doth export it from the left. Which doubtless is the reason, why the Vena Cava hath fleshy Fibres upon it, when it approacheth the heart. Nevertheless, we conceive the motion to be swifter in the Arteries, when the heart contracting itself, doth impel the blood into and through them; than when, dilating itself again, it doth intermit that its impulse. Which is true likewise of the blood in the veins, as may be sometimes observed in Phlebotomy, when the ligature is not so straight, as to cause much distension of the vein, in which the incision is made: for, in that case, the blood will flow forth more swiftly, every time the heart is contracted. And these are the Conditions of this admirable motion of the blood.  
Lastly, concerning the CAUSE of this motion; it is necessary that the blood be moved either by itself, or by some other principle: and if it be the Author of its own motion, then that must be in respect of either an inherent motive-Faculty, or of its Ebullition, or of its Rarefaction, or of its Quantity, whereby the Ventricles of the heart are distended, and so irritated as to discharge the same, by contracting themselves. If the motion be derived from an External principle; than it must be referred either to Attraction, or to Vection, or to Pulsion. Let us, therefore, see which of all these may be the most likely cause of the Motion of the blood.  
First, That the blood is not the cause of its own Motion, 
The blood, not the cause of its own motion, in respect of any motive Faculty, inherent in it.  ratione insitae sibi Facultatis, by reason of any inherent Faculty; may be inferred from hence, that in blood effused out of its vessels into the body, or any other receiver, no motion at all can be observed: and it is hard to conceive, that it should be so corrupted in a moment, as wholly to lose a faculty essential to it. Dr. Harvey, we confess, affirmeth, that he observed a certain obscure motion of the blood, in the right ear of the Heart (where He supposeth the motion of the Heart first to begin, and last to end) after the Ear had ceased to move; but we refer that to the Mication of the blood from the Vital Spirits not yet wholly extinguished.  
Secondly, That it is not the Author of its own motion, 
Nor, in respect of its Ebullition.  ratione Ebullitionis (which Arist. calls 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉) is manifest from these subsequent reasons. (1) No Ebullition can be constantly equal, or of the same tenor: but the Pulse of the heart, and so the motion of the blood, is, in temperate and healthy men, for the most part equal. (2) As the Ebullition is greater, so would the pulse; but in burning Fevers, the Ebullition is extreme great, by reason of the great intention of the heat; and yet the pulse is frequently small, and weak; as also in the beginning of putrid Fevers, as Galen long since remarked. (3) The blood suffers no ebullition, as it passeth through the heart. For, if in the dissection of a living Animal, you make an incision either into the left Ventricle of the heart, or into the Great Artery near it; you shall perceive the blood flowing out at the hole, to be pure and such as before it came into the heart, not frothy, boiling, or rarefied; and to continue such as at its first efflux: yea, more, if you receive the blood issuing from an incision of the Vena Cava, in one saucer, and that issuing from the left Ventricle, in another; you shall not be able to discern any difference betwixt the one and the other, either soon, or a good while after. An invincible argument against the Ebullition of the blood, first imagined by Aristotle, and since defended by many great men, his sectators. (4) The plunging an arm or leg into cold water, would suppress the Ebullition, and consequently the motion of the blood. For, if you apply a close ligature to a man's arm, and then immerge the same into cold water, or Snow; upon solution of the ligature, he shall find the blood returning to his heart, with so great a sense of cold, as very much to offend him. Which cold arising to the blood, from its being long detained in the extremities of the arm bound; Dr. Harvey will have to be the cause of swooning immediately after blood-letting, in many men; the heart receiving injury from that acquired cold.  
Thirdly, Not ratione Rarefactionis; because (1) in living dissections, 
Nor of its Rarefaction.  where the heart yet continueth its motion, no man ever hath, or can observe any such thing as rarefied blood to flow from either the left ventricle, or the Great Artery, if cut; but pure and such as is from the Ears let down into the ventrices. (2) The Heart itself, when cut in pieces, or wounded, may be observed to beat; yet not from any rarefaction of the blood, for than it hath no blood in either of its Ventricles, or Ears. (3) It hath been observed in Dogs, that after the point of the heart hath been cut off, and the remainder turned upside down, though the ventricles could not be half full, the blood hath yet been squirted forth at the top, even to the distance of three or four feet; which were impossible, in case the rarefaction of the blood were the cause of its motion. (4) The musculous flesh of the heart, is more firm and strong, than to be subject to inflation and detumescence, merely from the rarefaction of the blood. It must be a more forceible Agent, that moves that great and weighty machine of the heart. (5) If the blood were so much rarefied in the Ventricles, then certainly ought the orifices of the Vena Arteriosa, and Aorta, to have been much larger, because the blood would have required more room for its egress, than for its ingress. (6) The motion of the heart, and of its valves would be confused; for the Diastole of this, and opening of them, would happen at the same time, and consequently the valves would become useless; both which are repugnant to experience. Besides, the opening and shutting of the valves would be co-incident with the Systole of the Great Artery. (7) That the blood should be rarefied in the heart, and in a moment again refrigerated in the arteries; is contrary both to sense and reason: and if the rarefaction should so soon cease; why is it at all?  
It remains, therefore, that if the blood be the efficient of its own motion, it must be so only ratione Quantitatis, 
But of its Quantity distending the Ventricles of the heart.  by reason of its quantity filling and distending the Ventricles of the heart, and irritating them to discharge it, by contracting or shurting themselves. For, the heart being as it were burdened with the blood distending its cavities, doth contract its Fibers and so its Ventricles, to vindicate itself from that oppression; no otherwise than the stomach, guts, bladder, womb, etc. which being extended by meat, chyle, wind, urine, and the infant, drive themselves together, by the help of their Fibers, and so exclude that was burdensome to them. And thus is it probable, that the Heart is continually moved by the blood, like a Mill perpetually agitated by a stream of water; which stream being cut off, the motion instantly ceaseth. This may be credited upon the force of this one experiment; if the Vena Cava be intercepted by a ligature, so soon as the heart hath disburdened itself of what blood it hath received from thence, it instantly remitteth its motion; and upon letting in the stream again, by removing the ligature, it as suddenly recovers it. Than which there cannot be a more convincing argument, that the quantity of the blood flowing into the ventricles, is a cause of the motion of the heart, and so of its own motion.  
We say, A Cause; not the only cause: for we shall soon find another efficient as necessary and immediate, 
Th● blood not moved by Attraction;  to the motion, as the blood in the respect mentioned.  
That nothing doth Attract the blood either to or from the heart, is evident from hence; that in Nature there is no such thing, as the motion of a body by attraction; as hath been by solid and irrefutable arguments proved by that heroical wit, 
Apolog pro circulat sang. advers. Parisan. ●pag. 27. ad 49.  and most, accomplished Scholar, Dr. Ent; and also by ourselves, in the beginning of our discourse of Occult Qualities, whither (for expedition sake) we refer the unsatisfied.  
Nor is it moved, per modum Vectionis, by way of Carriage, 
Nor by Vection;  For, nothing can be imagined to carry along the blood in its course, but the spirits; and those would, in respect of their Levity, carry it only upward: but we see that the blood is moved also downward, and ad latera.  
It remains, therefore, that the blood is moved in round, 
But by Impulsion of the heart, endowed with a Pulsifick Faculty.  per modum Pulsionis, by impulsion, or protrusion: and the Impellent can be no other, but the Heart contracting itself, and so expelling the blood contained in its ventricles into the Great Artery, from whence it is urged, or pressed forwards into the smaller arteries, by the succeeding current. We conceive, therefore, that the Heart is endowed with a certain Motive-virtue inhaerent and essential, called the Pulsifick Faculty, which is conjoined, as a concomitant cause, with the blood itself, in giving it a due motion: whether it be, that this Faculty doth regulate the influx and efflux of the blood, which would otherwise be irregular; or that of itself it produceth the motion, which cannot be afterward continued, in case the flux of the blood be once interrupted. That this Faculty is necessary, may be inferred from these Reasons.  
(1) As the Pulse, so the influx of the blood would be always unequal, unless it were regulated by a Faculty. (2) When the blood is moved vehemently in Fevers, by the intense heat agitating and urging it; and in men at the point of death, propter extremos naturae conatus, by reason of Nature's agony and last efforts: yet is the pulse more weak and low, than at other times, because the Pulsifick Faculty is either much oppressed, or much weakened. On the other side, though the Faculty continue strong, yet is the influx of the blood much diminished, after large haemorrhages, or upon great obstructions of the capillary arteries and veins, in the habit of the body. Which consideration seems to us sufficient to import the necessity of conjoining a Pulsifick Faculty, with the quantity of the blood distending and so molesting the Heart, as a double proxime cause of the blood's motion.  
(3) Though the heart be cut in pieces, yet will each piece have a kind of weak pulsation, as long as it continues warm; which in all probability is to be ascribed to the Faculty implanted in all its Fibres, and not yet utterly destroyed.  
(4) It would be derogatory to the majesty of that Prince of all the parts, the Heart, to be moved by the violent impulse of an external principle, and itself conduce nothing thereunto.  
Notwithstanding these reasons alleged, we dare not set up our rest in this doctrine of the Ancients, concerning a Pulsifick Faculty implanted in the heart: only we have recited it, as the most probable Conjecture of all others, touching this abstruse Argument, the proxime Cause of the Motion of the blood. Nor shall we adhere to it longer, than until we shall be so happy as to meet with a more satisfactory solution of that admirable Phaenomenon. In the mean time, Modesty commands us to declare, that we find this Knot to be too hard and intricate for the teeth of our weak understanding. And well may we make this acknowledgement, when the subtle Frucastorius, after a long scrutiny into the same subject, was at length forced to desist, with Motum cordis soli Deo cognitum esse opinor; and that even Harvey himself professeth, that He found it rem arduam & difficultatibus plenam. We remember the modest say of two great Men, upon the like difficulties; the one of Galen, Quo pacto haec fiaut, si scrutaberis; 
lib. 15. de usu part. cap. 1. exercit. 307. num. 29.  convineeris te non intelligere neque tuam imbecissitatem, neque Opificis tui potentiam: the other of Scaliger, Quandam humanae sapientiae partem esse, quaedam aequo animo nescire velle; & veram sapientiam, nolle nimiùm sapere. And we think, we need say no more, in excuse of this our professed ignorance.  
Besides this Twofold Proxime Cause, there is also another Remote one, 
The Fabric of the heart, a remote cause of the motion of the blood.  viz. the Peculiar Conformation, or Fabric, of the Heart and its vessels. And among all the parts in this curiously framed Machine of the heart, those which are most official or instrumental to the motion, are the Fibers and fleshy columns; which serve not so much to the strength of the heart, as to the motion of it. For, in the Systole, all the Fibers, both small and great, as well those in the inside of the ventricles, as those in the Septum, or partition-wall betwixt them (like an artificial network made in the form of a purse) being contracted, or drawn together; the blood contained in the ventricles, must necessarily be expelled or pressed out of them.  
The Motion of the heart, which is called the Pulse, 
The Motion of the Heart described; as consisting of two● contrary motions, and a Respite betwixt them.  as being continual, and made partly by the influx of the blood, partly by the Pulsifick Faculty residing in the heart itself; doth consist of 3 things, the Systole, the Diastole, and the Perisystole: all which are to be explained by their proper Causes, according as ocular Inspection, and Reason doth dictate them to the understanding.  
(1) The Systole, being the proper and natural motion of the heart, is the Contraction or drawing together of the heart to a narrower compass, that so the blood contained in the right ventricle may be expelled through the vena arteriosa into the Lungs; and that contained in the left, may be expelled into the Great Artery, and so into all parts of the body.  
(2) The Diastole, being a motion only Accidentary to the heart, is a Dilatation, or opening of the heart, that the blood may flow into the right ventricle, out of the vena Cava; and into the left, out of the Arteria Venosa.  
(3) The Perisystole, is a certain quiet or short respite betwixt the Contraction and Dilatation of the heart, during the small time, that the blood is entering into, or issuing out of the ventricles. In healthy men, this pause is so short, as not to be distinguished from either of the two contrary motions: but sufficiently manifest in men at the point of death. It is also double, there being one respite betwixt the Systole and Diastole; and another betwixt the Diastole and Systole. And this is the natural state of the Heart.  
As to the Figure, or Form of the heart in those contrary motions; 
And the Figure of it in each.  from the dissection of Animals alive, from the commodity of its motion and quiet, and from the position of its Fibers and other parts, we have learned it to be thus.  
In the Systole, it may be observed that (1) the point of the heart is drawn upward toward the Basis of it, in order to the expulsion of the blood; the length of it being diminished, and breadth proportionately increased: because the basis is immovable, in respect of the cone, which is fastened neither to, nor by any vessels. (2) The inner walls, or sides toward the ribs, are brought nearer each to other; because they are constringed and made narrower, as may be perceived by putting a finger into either of the ventricles, at the time of their contraction: but the outward, becoming tumid, seem to be enlarged in latitude, from the contraction of all parts inflated in the tension or stretching. (3) The fore part of the heart is lifted up towards the sternum, and chief near the base; for, where the pulse is felt, there doth the heart strike the breast with its base, that part being lifted up, and brought near to the sternon: and at the same time (not in the Diastole) is the heart vigorated, and the arteries dilated and filled; and the pulses are felt both in the breast and wrist, the Diastole of the Arteries being coincident with the Systole of the heart. But the Pulse is more plainly felt in the left side, because there is the origine and orifice of the Aorta. (4) The whole heart becomes tense and hard, and contracted to a smaller bulk; as is manifest both to the sight, and to the touch. (5) The heart appears white, especially in imperfect Animals, such as Serpents, Frogs, Eels, etc. by reason of the expulsion of the blood in the Systole.  
In the Perisystole, when the heart is soft, lux, and in its proper state, (1) the cone recedeth from the base; and in some Animals, the base also recedeth from the cone: (2) The lateral parts, both the interior and exterior, are tended toward the ribs: (3) The anterior face of the heart sinks down, and the posterior is depressed, especially near the orifice of the great Artery.  
In the Diastole, which begins in the middle of the Dilatation, and ends in the middle of the Contraction. (1) the upper side is lifted up and distended by the blood falling into the ventricles out of the Vena cava, and Arteria venosa; the swelling sensibly beginning at the base, and progressing to the cone. But the base doth not them strike the breast, because the Arteries at that instant are contracted, and the heart ceaseth from expulsion of the blood. (2) The heart is flaccid and soft, because it is then only passive, in receiving the blood. (3) The sides become extense, and the cavities enlarged, and therefore if you put your finger into the heart, during the Diastole, you shall perceive no constriction, as in the Systole. (4) The heart appears red, because of the tenuity of its walls, and their repletion with blood. (5) The Cone receding from the base, makes the heart longer, that it may be more capable of blood. And thus doth the heart vary its Figure, in each of these three positions.   

OF THE DEPURATION OF THE BLOOD. Exercitation the Seventh.  
Of the Depuration of the BLOOD.  
FRom the Circulation of the blood, we (as Nature) advance to the DEPURATION or Defecation of it, from its unprofitable or excrementitious parts. And here we are to consider (1) the Generation, (2) The several sorts of Excrements generated in and to be separated from the blood, (3) The parts in which, and (4) The Manner how they are separated.  
Concerning the FIRST, we observe, that the blood being a heterogeneous liquor, 
The Genealogy of the Excrements.  consisting of various Elements or material principles (as the Element of which it is generate) and so not capable to be wholly changed into either the fuel of the Vital Heat; or Vital Spirits: when those parts of it, which had their Spirits less closely and firmly united to their grosser Elements, or (which is the same thing) which were most prone to volatility; are consumed and dispersed; it cannot be, but that the remains or relics thereof must thenceforth become not only useless, but also incommodious to Nature, and therefore as soon as may be, to be rejected. For the sweet and inflammable Spirits of the blood being exhausted; to what use can the remaining mass serve? It can be no longer the subject or residence of the Vital Heat, for the conservation whereof the blood is principally made: nay, if retained in the body, it would rather damnify and destroy the same noble principle, the Vital Heat. For, the Sulphur contained in the blood, doth by reason of the continual mication and endeavour of the Spirits to fly away and disperse themselves, and of the decocting activity of the Vital Heat exercised upon it, become adust, and contract a manifest bitterness and acrimony; and the Caput mortuum, or Terrene and grosser part, conjoined with the Fixative Salt, is apt to coagulate and to be p●trified; and the Phlegma, or insipid and viscid part is apt to obstruct the capillary arteries and veins, and so impede the Circulation; and lastly, the Aqueous part, or potulent matter, as being apt to render the blood too dilute and serous, is wholly unprofitable. These parts, therefore, being no longer useful ingredients of the blood, degenerate into Excrements; and aught to be sequestered from it.  
This Generation of the Excrements of the blood, may be appositely adumbrated by the Example of Wine distilled. For, 
Exemplified in the distillation of wine.  as Wine is a Liquor consisting ex Elementis primiceriis, of Various choice ingredients, or dissimilar parts: so is the blood. As the Spirits or more fugitive parts of Wine, are easily separable from the more fixed, viz. the Phlegm, Tartar, crass Sulphur, etc. by heat: so are the Spirits of the blood easily separated from the more fixed parts of it, viz. the Phlegm, Salt Tartar, crass Sulphur adust, the Aqueous or potulent matter, by the activity of the Vital Heat. As the Spirits of Wine are, by repeated destillations, advanced to that height of Volatility or subtlety, as that some of them fly away and are dispersed into air, in every rectification: so likewise are the Spirits of the blood, by repeated Circulations through the heart, brought to that degree of subtlety and volatility as that they cannot be longer contained or imprisoned in the body of an Animal, but penetrating through the pores, are exhaled by way of dry sweat, or insensible transpiration. And as the residue of the Wine, after the Spirits are gone, remains a dead mass, or vappa, consisting only of a Phlegm, Tartar, and crass Sulphur (which by long heat acquireth a bitterness and acrimony:) so doth the residue of the blood, after its Spirits are exhausted and dispersed. For, (as we said afore) the caseous and grumous parts of the blood, being brought to the state of Fusion, by the Vital Heat, make that excrement called the Phlegma: the Saline and earthly parts consociated, make the Tartar, which being dissolved and kept fluid by the potulent matter (to which it is easily mixed) make the Urine: and the crass sulphur, torrified by the Vital heat, and inseparably floating in the serum, makes the Bile, or Choleric excrement. And this Diversity of parts in the blood is evident even to the sense, in blood let forth of either vein or artery into a vessel. For, there the caseous or grumous parts (which being most elaborate, and brought to a certain degree of Fusion, have thereby acquired a viscidity) swim on the top, in the form of a whitish film or membrane; while other parts of the same kind, having not attained to the like degree of Fusion and viscidity, sink to the bottom; and the serous or watery (impregnated with the Salt, and somewhat of the crass Sulphur adust) flow round about the rest.  
Concerning the SECOND, viz. the various sorts, 
The Various sorts of those Excrements: and their Definitions.  or Kind's of Excrements to be separated from the blood, in order to its purification; though what we have now said, concerning their Original, may seem to intimate their several Families and specifical Differences: yet will it not be superfluous to observe further, that all of them, being Liquid, fall under two General Kind's. The First comprehends the More Thin Excrements, which are (1) the Urine, impregnated with the Tartar, (2) the Sweat, (3) the Tears, and (4) the thin liquor contained in the Lymphducts: The Other includes the Less Thin, which are 1) the Phlegm or ptuituituous Mucus: whether it be Acid, such as is found in the stomach and guts; or Insipid, such as the Rheum distilling from the brain by the palate and nose, the spittle, and salivous moisture excerned from the Glan●ulae sublinguales; (2) the Bile, both that which is collected in the bladder of the Gall, and that deposed in the cavities of the Ears, called the Earwax; for these two seem to be cousin germane, and differing only in consistence.  
The Urine, is a serous excrement, impregnated with Tartar, and tincted with a small portion of the Bile; brought by the Emulgent arteries, into the Kidneys, together with the blood; there separated from the blood, by a kind of percolation, thence distilling by the Ureters into the bladder, and at length avoided by the urinary passage.  
The Sweat, is likewise a serious excrement, impregnated with a small quantity of Salt, expulsed out of the capillary arteries into the habit of the body, and thence excerned through the insensible pores of the skin.  
Tears also are a serous and brackish excrement, imported by the arteries into the Carunculae Lachrymales; or small Glandules, placed in the interior corners of the Eyes; there separated, by a kind of percolation, from the blood; and thence expressed, for the most part voluntarily, in grief, and sometimes in sudden and profuse joy; and sometimes involuntarily, in pain, fevers, etc.  
The limpid Liquor found in the Lymphducts (at least a good part thereof) is a mild and insipid exhalation of the blood in the arteries, sweeting through the coats of the smaller arteries, collected by degrees in the Lymphducts, and by them again infused into the blood, as well to prevent the coagulation, as to promote the mication thereof; and after various Circulations, avoided by evaporation through the skin.  
Among the Less Thin Excrements,  
The Phlegmatic mucus found in the stomach, is a thick viscid excrementitious juice, endowed with some Acidity, brought into the coats of the stomach, by those branches of the Celiacal artery, which are therein terminated there secerned from the blood, and by transudation immitted into the cavity of the stomach; to the end, that it may serve to excite the Appetite, and in place of a Ferment, promote the dissolution and concoction of the meat.  
The Pituitous Mucus found in the Guts, is an insipid excrement spewed out of the Mesenterick arteries, into the substance of the guts, transmitted by insensible passages into the hollow of them; serving to defend them from the injuries of the Chyle and excrements of the belly passing through them, and at length to be excluded together with those excrements, by stool.  
That distilling from the Brain, is a pituitous excrement, severed from the blood brought thither by the Arteries, and excerned either by the Palate, or nostrils. Such also are the sputum, which falls down from the pituitary Glandules situate about the basis of the brain: and the saliva, which is generated of humours imported into the Almonds of the Ears, the Glandulae sublinguales, and other spongy parts in the jaws and mouth, and therein separated; for the moistening of the mouth, and softening of the solid meat, in mastication.  
The Bile, or yellow Choler found in the bladder of the Gall, is a bitter excrement, generated in the blood, of the crass sulphur thereof (dissolved by the serum) made adust by the vital heat; separated in the Liver, and thence conveyed by convenient vessels (which we shall particularly mention anon) into the Intestines, to be excluded with the excrements of the belly.  
Lastly, the Earwax is a bilious excrement, thick, yellow, and bitter, in small quantity effused out of the capillary arteries near the Ears, and collected in the meatus auditorius.  
The Material principles, Generation, Differences, and particular Essences of these Excrements, 
The Reason, why each particular Excrement is determinately imported into the part particularly comparated for its separation; is  being thus explained; it follows that we now discuss the Manner of their separation from the blood, in the parts specified, framed by Nature to that end. Which that we may do with the more satisfaction and perspicuity; it is requisite, that we premise some short disquisition, as well concerning the Reason, why such or such Excrements (all being promiscuously blended together, or flowing confusedly together in the arteries with the blood) are yet carried into such or such parts, rather than into any others: as concerning the various ways Nature hath contrived, for the separation of Humours each from other, in the body. For, these Generals being explicated, anticipate the remove of many of those difficulties and obscurities, that we shall encounter in our scrutiny into Particulars.  
Concerning the Former, therefore, we advertise; that the Reason, why the Acid Phlegm contained in the blood, is imported rather into the Stomach, than into the guts; the Insipid Phlegm rather into the Guts, than into the stomach; the serum into the Kidneys, rather than into the Liver; and the Bile into the Liver, rather than into either the Stomach, Guts, or Kidneys: we say, the reason of this, is not that each particular Excrement is so directed, by any Intelligent Faculty, whose office is to distinguish not only the excrementitious parts of the blood from the benign and profitable, but also the excrementitious one from another, and to dispense each to the part ordained for its separation: nor that each excrement is attracted by and to its like, as if the Phlegm preexistent in the stomach and guts did, by reason of similitude of substance, draw to itself those Phlegmatic particles of the blood, that hold the nearest analogy to its own nature; and so of the serum in the Kidneys, the Bile in the Liver, Porus bilarius, and bladder of the Gall, etc.  
Not by any Intelligence, 
Not, that it is so directed by any Intelligence, or distinguishing faculty.  or distinguishing Faculty; because the soul, or Mind (whose Function is only to rationate, or think) is conscious to herself of all her actions; but no man's soul is conscious of any such act, as the distinction of Excrements: And to assign a distinct Faculty to every distinct operation in the body, is (as that wonder for Wit and Learning, Dr. Ent, acutely said) Deos advocare in theatrum, ut solvant nodum fabulae.  
A course frequently taken, and eagerly pursued by many Philosophers even of the highest form; but, in truth, so manifestly erroneous, as to refute itself. For, those fruitful imaginations, that first hatched and introduced the Faculties Attractive, Retentive, Concoctive, and Expulsive; might, if they pleased, have invented and added as many more to preside over each particular humour and Excrement in the body, and multiplied them even to infinity: the difference of those Actions (and indeed of all others done in Animals) arising really from the different constitutions and structures of the organs, wherein they are performed.  
Nor by Spontaneous Coition, or Attraction Similary; 
Nor that it is Attracted by the like Excrement contained in that part:  because in Nature there is no Motion by Attraction, but all from Impulsion; and if there were, yet could not one excrement draw, another of the same kind, because Simile non potest agere in simile, quà simile; non magis certè, quàm in seipsum. To which we may add, that though many great men have laboured much to assert this opinion of Attraction propte● 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 by reason of similitude or familiarity of substance: yet could none of them make it so much as intelligible; and therefore Regius did well to say, Excrementorum attractio & spontanea coitio, sunt rejiciendae, quia non sunt manifestae vel intelligibiles, nec probatae.  
To what, then, shall we ascribe this so admirable effect? 
But, that there is a certain peculiar Conformity of magnitude and figure, betwixt the minute particles of this or that Excrement, and the pores of this or that part constituted for the reception of it.  Why truly, according to the most of probability, to nothing else, but the Correspondence of Magnitude and Figure betwixt the minute particles of this or that peculiar excrementitious humour to be separated from the blood, on one side; and the small passages leading into, and insensible pores in this or that part, peculiarly constituted for the separation thereof, on the other: together with the help of that particular Fermentation, which each humour doth suffer either near unto; or in the place of its separation; to Nature nothing being more frequent, than to make use of a certain Fermentation, greater or lesser, where she intends a separation of various humours one from another.  
For, since each particular Excrement doth consist of particles of a determinate Magnitude, and determinate Figure; and that each separatory organ in the body hath likewise not only a distinct manner of Conformation of its conspicuous vessels, parenchymas, and other sensible parts; but also its insensible particles, passages, and pores, of a particular magnitude and figure, different from those of all other organs, and accommodated only to that Action or Office, for which the same was made: it is highly reasonable to conceive, by way of inference, that the blood being diffused through the arteries, by the impulse of the heart, indiscriminately and equally to all parts of the body; yet each part doth admit and receive only those parts of the blood, which in respect of the magnitude and figure of their minute particles, are most correspondent or agreeable to the magnitude and figure of its slender passages and pores; and exclude the others, wherein is no such analogy or suitableness. And hence, doubtless, is it, that the serous part of the blood is determinately imported into the Kidneys; the Phlegmatic into the stomach, and guts; the Bilious into the Liver, etc. rather than into any other parts: the capillary branches of the arteries, and the insensible pores of the substance of each of those parts, being in magnitude, figure and situation respectively accommodated or adapted to the receiving and imbibing of the humour brought to it.  
And for the Separation of each of these Humours thus admitted into these or those parts; 
Which is also the Cause of the Separation of particulas● Excrements, in particular parts.  we conceive it likewise to belong to the very same Cause, as their Reception or Admission doth; viz, to the determinate magnitude and figure of the insensible passages and pores in the Parenchyma of this or that part. Because the separation of each Excrement is effected by a kind of Cribration, or Percolation; and in all percolations, the particles of the matter transmitted, ought both in magnitude and figure, to hold an analogy with the pores of the body, through which they are transmitted. Now, that the Parenchymata of the separatory organs named, are endowed with various secret passages and pores of different magnitudes and figures; is manifest from hence, that their component particles are variously contexed, (in one more loosely, rarely and thinly, in another more closely, densly and thickly) and the vessels and Fibers running through them as variously form, in magnitude, longitude, position, number etc. and where such variety is, it doth necessitate an equal diversity of pores, which are nothing else but the void spaces betwixt the solid particles. And, that these Excrements may be (to omit, that they are) easily transmitted through such narrow and slender passages and pores; however inconspicuous and undiscernible by the sense; cannot appear difficult, or incredible to any man, who shall but observe, how blood will issue forth of the skin, if it be pricked with the point of even the smallest needle. And thus much of the Former part of this previous Disquisition.  
As for the Other; though the Colatures, which Nature hath instituted, 
The Differences of Colatures, used by Nature in the separation of Humours in the body.  for the separation of Humours in the body, be manifold and various: yet may they all be commodiously reduced to Two Kind's, all being in order either to Nutrition, or to Excretion.  
Of the First Kind, we have an example in the Nutrition of the Fibers and Membranous parts of the body. For, it is most probable, that those parts (if not all the rest) are nourished by the Succus Nutritius, brought to them through the Nervs; and that Aliment, being somewhat glutinous, like the white of an Egg, cannot easily penetrate into their substance, without the help of a certain thin and watery vehicle; which having once done that office of introducing the succus nutritius into these parts, becometh thenceforth unprofitable to them, and so is presently discharged by the Lymphducts into more ample spaces.  
Of the Other Kind, there are Three distinct sorts. Whereof the First is, when the thicker humour is retained, and the thinner rejected: of which we have an example in the Kidneys, where the serum is transmitted into the Ureters and bladder, while the pure blood is retained, to be returned into the vena Cava, by the Emulgent veins. The same is also effected in the separation of Sweat, Tears, and spittle.  
The Second (contrary to the first) is, when the thinner humour is retained, and the thicker rejected; as in the coats of the stomach and guts, where the Mucous Excrement or Phlegm is transmitted into their cavities, and the blood retained to be sent by the veins into the vena portae: and in the brain, in which the like Mucus is separated from the blood, and deduced into the palate and nostrils.  
The Third, when two humours of equal consistence or thickness are separated one from the other, this being retained, and that rejected. And this Colature is performed in the parenchyma of the Liver, For, the Fellous humour, and the blood, while warm, are very ●eer of equal thickness: and yet hath nature found out a certain way of percolation, which easily distinguisheth and separateth them each from other A thing far transcending the industry of man, who can make no Artificial Colature, by which two Liquors of equal consistence may be separated one from another.  
These Considerations premised in the General, we now at length come to explicate the Particular Manner, how each Excrement is separated, in its peculiar place.  
The blood in its Circulation, being, by the pulse of the heart, 
The Reason and Manner of the separation of the serum from the blood, in the Kidneys.  impelled into the Emulgent Arteries, flows along into the several branches, or ramifications of them, and at length into the smaller succses, or capillary arteries, which running out into smaller and smaller threads, till they become inconspicuous, lose themselves in various parts of the substance of the Kidneys, infusing the blood yet commixed with the serum, into the same. This Parenchyma or substance of the Kidneys, consisting of various parts diversely contexed and conformed, and having Pores of different magnitudes and figures and positions running through it, whereof some pores are more accommodate in magnitude and figure, to the minute particles of the blood, and others more correspondent to those of the Serum: the blood taketh its way through one sort of pores, into the capillary branches of the Emulgent veins, that lie open and ready to receive it in all parts of the parenchymas, and thence to lead it along into the Vena Cava; and the Serum taketh its course through the other sort of pores, into the Papillary Caruncles, which being pervious into the branches of the Ureters (in like manner variously dispersed up and down, so as to receive it from the Car●ncles) convey the same into the trunks of the Ureters themselves, from whence it spontaneously destilleth into the Bladder, which by contracting of its self expelleth it in Urine. And this we conceive, to be the true manner of the Percolation of the Serum, made in the substance of the Kidneys.  
When the Celiacal and Mesenterick Arteries have, by those their branches, 
Of the Phlegmatic Excrement, in the stomach and guts.  that tend to those parts, brought the blood not yet purified from the Phlegmatic Excrement, both Acid and Insipid, into the capillary arteries disseminated upon the coats of the Stomach and Intestines: in which there is a diversity of Pores or insensible passages, some direct, some obliqne, in a word, some, in respect of their magnitude, figure and position, peculiarly accommodated to the admission of blood; some to the admission of Acid Phlegm; and others to the admission of Insipid: it comes to pass, that by reason of this Diversity of secret passages, the blood is impelled into the pores most analogous to its minute particles and through them into the capillary veins respondent to the capillary arteries, and thence into the larger veins, which soon discharge it into the Vena portae; while the Acid Phlegm is protruded forward into those pores, that are most conformable to its minute particles, and through them at length into the cavity of the stomach; and the Insipid likewise is transmitted through those pores, that are most Sy●●bolical to the magnitude and figure of its minute particles, into the cavity of the Guts, there to defend them a while from the injuries of the Chyle and Excrements, and upon the accession of a new supply of the like insipid Phlegm, to be excluded together with those excrements, as we said before. And this we conceive to be the way of percolation Nature useth, for the separation of the Phlegm from the blood, in the stomach and intestines.  
Thus long doth the Bilious Excrement inseparately accompany the Phlegmatic, flowing along together with it through the branches of the Celiacal and Mesenterick arteries, 
That the Bilious Excrement doth accompany the Phlegmatic, to the stomach and guts; and why.  into the coats of the stomach and guts; but, when it once comes there, it leaves its associate, the Phlegm, to be, after the manner expressed, transmitted into their cavities, and being throughly commixed with the blood, is propelled into the extremities of the capillary veins, answering to the extremities of the capillary arteries, that brought it thither; and from thence is carried along into Vena portae, and at length into the substance of the Liver, therein to be segregated from the blood. Nor, indeed, ought this Bilious Excrement to be sooner dissociated from the Phlegmatic; or conveyed by any nearer way, or shorter cut, in direct vessels tending from the descendent trunk of the great artery, to the trunk of the vena portae; and that for Three important Reasons.  
First, it seems necessary that the Bilious humour should accompany the Phlegm, until it hath brought the same into the substance of the stomach and guts; because the Phlegm, being a mucous and visoid humour, would be apt to obstruct the capillary vessels, and insensible pores of those parts, unless it were made more dilute and penetrative, by the admixture of the Bile, an humour penetrative and detergent, and so fit to prevent obstructions. This reason may receive verification from hence, that Men of a hot and choleric constitution, and such in whom this Bilious Excrement doth abound more than in others, are seldom or never troubled with obstructions of the stomach and guts, by gross and viscid humours: whereas, on the contrary, those of colder complexions (especially Virgins Leucophlegmatique and afflicted with the Green-sickness) in whom less of choler is generated, are commonly oppressed with oppilations of those parts, from abundance of tough and tenacious phlegm.  
Secondly, the Bilious humour itself seems to require some certain degree of preparation, conductive to its future separation, before it can be commodiously imported into the Liver. For, should it be conveyed into the Liver, directly out of the descendent trunk of the great artery; it could not be avoided, but some part of the Phlegm would also be carried along with it: because those humours, while they remain in the arteries, are never actually separated; and when they are, their separation is made, by the recess or going off of the Phlegm into the stomach and guts. And if any part of the Phlegm should accompany the blood into the Liver; the Liver would always be inevitably obnoxious to great obstructions, such as would soon render it unfit for the office, by Nature assigned unto it.  
Thirdly, the Bile certainly is more firmly united to the blood, than the Phlegm; as being essentially radicated in the serous part thereof, so that without some further preparation, it cannot be easily severed from it. And therefore it was requisite, that the Bile should be carried about by those ambages of the stomach and guts, that by passing through those intricate meanders, it might acquire some disposition preparatory to its succeeding separation. Now, that which gives it this previous disposition, is a peculiar Fermentation, which it undergoes in the vessels leading it along into the trunk of the Vena portae: it being most undeniable, that the speediest means in Nature, for the separation of impure humours from pure, is by Fermentation, as may be sensibly exemplified in Wine and Beer, which are soon defecated by the help of Fermentation, but never without it. These Reasons, therefore, make it evident, that Nature was guilty of no oversight or rashness, when she ordained, that the Bilious Humour should be thus carried about through such indirect and long ways, before it arrive at the Liver; seeing that circulation doth make its separation afterward both the more safe, and more easy.  
Nor did Nature play the wanton, or supererogate, when she contrived, 
Why the Blood is not carried immediately out of the trunk of the vena portae, into that of the vena cava; but through the various meanders in the Liver.  that the blood should be carried along through all those intricate labyrinths in the Liver; forasmuch as if the blood were to be infused into the trunk of the vena cava, by some vessel immediately and directly tending from the trunk of the vena portae, the Bilious humour, being not yet separated from it, would necessarily pollute and corrupt the whole mass of blood. To avoid that inconvenience, therefore, was it requisite, that the blood should be first diverted into the Liver, and therein defecated from its remaining impurities, before it be permitted to enter the vena cava.  
When it is brought into the Liver, it doth not pass through the capillary branches of the vena portae, 
And why it is transmitted through the Parenchyma of the Liver.  into the extremities of the capillary branches of the Vena cava, immediately or per anastomosis, as was long believed and taught by Anatomists; because we have the testimony of our eyes, that there are no such anastomosis, or mutual Inosculations betwixt the extremities of those vessels: but, it is first percolated through the Parenchyma or very substance of the Liver. Now, to what end is it so percolated? That percolation must certainly be in order either to some Alteration, or to some Separation. It cannot be in order to any Alteration, because no such thing can be imagined to be effected in the Liver, since the Liquor passing through the Liver, as it came-in blood, so doth it go out blood. It must, therefore, conduce to the separation of something from the blood. And that something can be nothing but the Bilious Excrement; because all other Excrements are separated, before the blood arrive at the confines of the Liver: and because no other Excrement can be found therein. Which consideration is alone sufficient to evince, that the Office of the whole Liver, is to receive the blood out of the vena portae, to purge it from the Bilious Excrement, and to discharge it so purified into the vena cava, thence to be conveyed into the Heart.  
As for the Manner how this excellent work of Purification is performed in the Liver; for the better understanding the same, we are to observe.  
(1) That the Parenchyma is the Principal part among all those many, that make up that ample and curiously contrived organ of the Liver. 
That the Parenchyma is the Principal part of all the Liver.  In particular, the Ligaments of the Liver serve only to establish, or hold it firm in its natural position; the Coat investeth it; the vena Portae brings the blood into it; the Capsula Communis is inservient to the distribution of the same blood, through the branches of the vena Portae; the Hepatick Artery and Nerve serve partly to the better promotion of the blood into all parts of the parenchymas, and partly to the more quick and easy influx of the Bilis into the Porus Bilarius; the branches of the Vena Cava export the blood, after its purification; and those of the Porus Bilarius export the Bile, after its separation: so that it is manifest, that all these several parts are in some sort or other, mechanically inservient to the Parenchyma; and that the Parenchyma is the sole part, wherein the separation of the Bile from the blood is made by an admirable artifice of percolation.  
(2) That this Parenchyma is a kind of Streiner, after a peculiar manner framed by Nature, 
And a kind of Streiner;  for that separation, which can be no otherways effected, but by Percolation. For, whensoever a mixed Liquor is brought into a part, and in passing through that part severed into two distinct kinds, and so by distinct ways effused out of it again; we may be certain, that those Liquors were severed each from other by percolation made in that part; and as certain that that part is a Percolatory Instrument. And since the very same is effected in the Parenchyma of the Liver, while the Bile is severed from the blood; we may well conclude, that that separation is made by percolation, and that the Parenchyma is a kind of Streiner.  
(3) That this Parenchyma being a lax and spongy substance, after a peculiar manner contexed, 
Whose particles are contexed after a peculiar manner, and pores of divers sorts: in respect whereof, the Bile is therein separated from the blood, mechanically.  and having various sorts of pores, whereof some are in magnitude, figure and situation, particularly comparated for the reception of the impure blood, effused out of the extremities of the capillary branches of the vena portae; and others in like manner particularly comparated for the reception of the minute particles of the Bilious Excrement, and the transmission of them into the extremities of the capillary branches of the Porus Bilarius; and others again particularly comparated for the reception of the minute particles of the pure blood, and the transmission of them into the extremities of the capillary branches of the vena cava: we say, these things being so, it is reasonable to conceive, that after the impure blood is brought into the pores of the First sort, the particles of the Bile are impelled into those of the Second, and through them into the extremities of the capillary branches of the Porus Bilarius; and the particles of the pure blood into those of the Third, and through them into the extremities of the capillary branches of the vena Cava; so as the separation of the Bile from the blood, is made in the parenchyma of the Liver, 
The same inferred from 4 considerables: viz.  only by reason of this diversity of its pores.  
To increase the verisimilitude of this Opinion, there occur 4. things not unworthy a serious remark, in this place; viz.  
(1) That the Capillary branches of each sort of the vessels mentioned, 
The equal distribution of the capillary branches of all the vessels in the Liver.  are distributed equally into all parts of the Parenchyma; so that the Port-vein doth dispense the blood equally into all parts thereof; and the capillary branches of the Porus Bilarius, being likewise disseminated through all parts of the same, lie ready to admit the Bilious●humor, as fast as it is separated from the blood; and the capillary branches of the vena cava, being also dispersed into all parts of the same, are ready to receive the pure blood, as fast as it is defecated from the Bile. Which is some document, that this whole work of purifying the blood from the Bilious humour, is performed in the Liver, only Mechanically, and that with the greatest facility imaginable: nor is it possible for the greatest wit of man, to imagine any fabric more commodious for the effecting thereof, than this of the Liver is.  
(2) That the Vena portae, 
The Pulsation of the Vena Portae within the Liver.  being entered into the body of the Liver, doth acquire a certain Pulsation (though weak and less perfect than that of an Artery) by the benefit partly of the Capsula communis, that includeth it, and partly of the Arteria Hepatica, that accompanieth it. For, being included in the same common case with the Arteria Hepatica, it must necessarily be compressed, in some measure, by the systole thereof; and again be relaxed, in the diastole: and by that means suffer a certain Dilatation and Compression alternately. And being so compressed, it must impel the blood into the parenchymas; and that blood must be driven on by the next succeeding blood: so as that the motion and distribution thereof is necessarily continued by that impulse, without the necessity of any either Similary Attraction, or Distinguishing Faculty.  
(3) That the Hepatick Nerve may be conceived also to conduce somewhat to that Pulsation of the Vena Portae. 
The assistance of that Pulsation, by the Hepatick Nerve.  For, that Nerve also is included in the Capsella Communis, and no less distributed upon the same, than upon the branches of the Porus Bilarius. And, therefore, when the Arteria Hepatica is dilated, this Nerve, as being contiguous to it, must be somewhat compressed; and so irritated to make some small Contraction of itself: which being impossible to be effected, without a proportionate constriction of the Capsula Communis; it comes to pass, that the Vena Portae included in the same Capsula, suffereth a constriction, at the same time.  
(4) It is probable, that this Pulsatile motion of the Vena Portae within the Liver, 
The Resuscitation of Vitality in the blood, in the branches of the Vena Porlae, within the Liver; and a new Fermentation thereof, praevious to the separation of the Bile.  doth cause some new Fermentation of the blood, and redintegrate the decayed Vitality thereof, in such a proportion, as may be sufficient to vivify the Parenchyma of the Liver, and conduce to the more easy and speedy separation of the Bilious impurities therein: especially considering that the Spirits of the blood brought in, are hindered from flying away (as they usually do through the thinner coats of the veins) by the thickness of the Capsula Communis, and so kept together to resuscitate the Mication and renew the Vitality thereof. That this is so, may be in part inferred from hence, that the Vital Spirits can be no otherwise communicated to this Parenchyma; the Arteria Hepatica being wholly distributed upon the Capsula Communis, and the branches of the Porus Bilarius, but never touching the Parenchyma with so much as one small surcle. Now there being no vessel that brings blood into the Parenchyma, but only the Vena Portae; that Parenchyma must of necessity be deprived of all Vitality, unless we allow the blood, brought by the Porta, to recover its vital disposition, by the means of the Pulsation caused in the Porta, and the excitement of a new Fermentation from the restraint of the Spirits. For, without the influx of vital blood, no part can be vivified: and certain it is, the Parenchyma doth receive no blood, but only from the Vena Portae. This Resuscitation of the Vital Spirits in the blood, brought into the Liver, may be adumbrated by the example of the heart of a Viper, or other Animal of like vivacity. For, the Heart being cut out of the Viper yet alive, and placed upon a table, doth a good while retain its pulsation; and as that motion gins to decay, by reason of the consumption of the Vital Heat, if you but drop some warm liquor upon the then languishing heart, it will instantly revive, and beat again, until it grows cold. And such doubtless is this small spark of life re-enkindled in the blood contained in the Vena Portae, within the Liver: which though but small, may yet be sufficient both to enliven the Parenchyma, and to excite some gentle Fermentation in the blood, conducible to its purification in that place.  
Now, to bring all this into a narrower circle; if we reflect upon the Equal Dissemination of all the foresaid vessels through all parts of the Parenchyma; upon the Pulsation of the Vena Portae, within the limits of the Liver, whereby the motion of the blood is made more strong and quick; upon the promotion of that pulsation, by the Hepatick Nerv spontaneously contracting itself, after every diastole of the Hepatick Artery; and lastly upon the resuscitation of Vitality in the blood, and its renewed Fermentation (which always precedeth the separation of any humour from the blood): we say, reflecting upon these things, we may plainly understand, with how little of difficulty the blood is impelled into all parts of the Parenchyma, and therein separated from the Bilious impurities, only by reason of the Diversity of Pores in the same Parenchyma, according to a MECHANICAL way or method. Which was the difficulty that required to be removed.  
When Excrements are separated, they must be Excluded; 
The various Manners of the Excretion of Excrements, after they are separated and collected.  and therefore, having investigated the manner of their separation from the blood, it is requisite that we say somewhat of the Manner of their Excretion. For albeit there be no Excretion, but what is effected immediately by Pulsion; yet doth that Pulsion arise from various causes. In particular, One sort of Excretion is made by simple Propulsion; as that of the Serum through the substance of the Kidneys, that of the Bile into the bladder of Gall, and into the Porus Bilarius, and of the Phlegma into the Guts. Another is, from the Rarefaction of the Excrements themselves; as when the Serum, flowing together with the blood in the arteries, is rarefied by heat, and breaks forth into the habit of the body, whence at length it is excluded in sweat through the pores of the skin; and when the watery part of the blood is by way of Exhalation transmitted through the coats of the smaller arteries, and collected in the Lymphducts. And a third sort of Excretion is made, merely by the Spontaneous Contraction of the Parts Expelling; such is that of the Bile out of the bladder of Gall, into the ductus communis; of vicious humours out of the stomach, by vomiting; and of the Urine out of the bladder, etc. So that we see, there is as little need of any Attraction, toward the Excretion of Excrements, as there was toward their separation from the blood.  
To Explicate the Manner of the Excretion of the Bile somewhat more particularly; 
The particular Manner of the Excretion of the Bile.  we note, that the Porus Bilarius is filled with that humour, by its capillary branches disseminated into the greatest part of the Parenchyma of the Liver: and the Vesicula Fellis, by its Fibrous roots, that are likewise disseminated into the rest of the parenchymas. And when these two Receptacles are thus filled with this humour, even to distension; then, being irritated or molested by that burden, they contract themselves, and so squeeze out so much thereof, as exceeded their natural capacity: the Vesicula Fellis exonerating itself by the Meatus Cysticus, and the Bilarius Porus by the Ductus communis, out of which the excrement is convaid, by the obliqne insertion, into the Guts. Which Irritation and contraction of these Receptacles, is the cause, why the Bile doth not continually and by drops distil out of the Ductus communis into the Guts, as the serum doth into the Ureters: but is as it were eructated by intervals, and in good quantity at a time; those concave and membranous parts never contracting themselves, but only when they are above measure distended by a redundancy of the humour contained in them; and the efflux of the humour depending wholly upon that their Contraction.  
That these parts do thus Contract themselves, is inferrible from hence, 
And the Cause thereof,  that all sensitive parts (among which the vesicula Fellis may be accounted, in respect it enjoyeth a small Nerve derived from the sixth conjugation) are capable of Irritation: and therefore, whenever they are distended beyond their natural rate, or otherways molested; they begin instantly to make some resistance, and reduce themselves to their due laxity, by ex-pressing what was offensive to them; and if the parts thus irritated, be concave, membranous, and fibrous, it is necessary, that their resistance be made by a Contraction of all their Fibers, whereby their cavity is lessened, and some part at least of the humour distending them, is expelled. The Receptacles of the Bile, therefore, being such parts; they must have such a motion of self-Restitution, upon the like occasion.  

Digression.  
Here (methinks) I perceive my Reader to put on the cloudy aspect of dissatisfaction, 
PARADOX. That we have a certain Natural Feeling wholly distinct from the Animal, and independent upon the Brain.  and to arrest me with this curious scruple, saying; Doth not this Irritation and spontaneous Contraction of Membranous and Nervous parts, when they are molested, imply a certain sense in them, distinct from the sense of Feeling or Touching, and independent upon the Common sense, or Brain? For, whatever is any ways moved by itself, in avoidance or resistance of what is offensive to it; must be endowed with a sense, whereby to discern that offensiveness: according to that rule, quicksands quid contra irritamenta & molestias, motibus suis diversis nititur; id sensu praeditum sit, necesse est. But we are not conscious to ourselves of any such sense within us (as we are of all our Animal senses) whereby those parts are made sensible of their irritations; and therefore it seems, you have imagined one sense more than Nature hath made.  
For the solution of this Difficulty, therefore, we Answer; that those Motions and Actions, which Physicians call Natural (because they are not instituted by the Will; but done even against it, and cannot be moderated, accelerated, retarded, or suppressed, ex Arbitrio nostro, at our pleasure: and so have no dependence upon the Brain, that is the Common instrument of all the senses) these motions and actions, we say, are not yet made without some sense, naturally inhaerent in the parts moved. For instance; we are certain, that in palpitations, tremble, syncopes, swooning fits, and other Cardiacal symptoms or affections, the Heart doth variously move, and agitate itself; as being offended with something preternatural and noxious to it, and irritated to resist and repel the same: and this in respect only of some sense or feeling, by which it discerneth what is incommodious and harmful. The stomach and Guts, in like manner, being oppressed and provoked by vicious humours, instantly rise in arms, and raise impetuous vomitings, nauseousness, convulsions, fluxes of the belly, and the like motions, for the expulsion of their enemies: and as we have it not in our power, to excite or suppress those commotions; so have we no particular cognisance of any such sense, which should extimulate those parts to begin and continue them. Truly, we cannot but wonder, as oft as we observe the effects of Antimony infused in wine, and taken into the stomach. It is not our Taste, that doth distinguish the tincture of the Antimony, from the wine; nor are we sensible of any disagreeableness therein to our nature, while we are swallowing it down: and yet in the stomach there is a certain sense, that discerns the offensiveness of that draught, and quickly engageth the stomach to raise and contract itself, and to eject it again by vomiting; nor will it ever cease, till it be wholly discharged. Consider, how even the Flesh itself doth presently distinguish a poisonous puncture, from a simple one; and how soon it contracteth, condenseth and fortifieth itself, to expel the venom, whereupon ensue swelling, inflammation, and great pain in the part pricked, as is observed in the stinging of Bees, and Hornets, and Scorpions, and the biting of Spiders, Vipers, and other venenate Animals; and all this merely from some sense, which teacheth the flesh that difference, and excites it to make resistance. Consider further, how the Contorsion, Falling down, Ascent, suffocation and other violent Agitations of the Womb in women; proceed not from the brain, or Common sense, but from a Natural sense inhaerent in that part, without which it could not be provoked to those impetuous strive and motions. For, whatever is wholly destitute of fence, is wholly uncapable also of being irritated to perform any action or motion, in order to its safety. Nor can we, indeed, otherwise discern what is Animate and sentient, from what is Inanimate and void of sense; but only by some Motion excited in it, by something molesting and irritating it: which Motion doth continually both follow and argue sense.  
To evince this Natural sense yet further, we shall thus reason. We find in ourselves, that we have Five External Senses, by which we perceive objects without us; but, because we do not perceive our perception, by the same sense, by which we perceive objects (for, we see with our eyes, but do not by them perceive that we see; but by the mediation of another internal sense, or sensitive organ, the Brain, by which we judge of all objects offered to the External senses): therefore is it manifest, that the common sensory is the Brain, which together with all its Nerves, and external organs annexed to those nerves, aught to be held the adequate Instrument of sensation. And we may fitly resemble it to a sensitive Root, which shooteth forth many Fibers or strings, whereof one doth see, another hear, a third taste, a fourth smell and the fifth feel.  
Nevertheless, As Experience assureth us, that there are some Motions and Actions in us, whose regiment or moderation is no ways dependent upon the Brain; and therefore, by contradistinction to voluntary or Animal motions and actions, they are named Natural: So also doth Reason teach us, that we have a certain sense of Feeling, which is not referrible to the Common sense, nor communicated to the Brain, and of which we take no cognisance, but by the various effects and commotions that it causeth in our bodies. For, in this Sense, we do not perceive that we feel; but as it fares with men distracted, or otherwise agitated with any violent passion of the Mind, who neither feel pain, nor take notice of objects offered to their senses: so is it with us in this Sense, which operating without our knowledge, is therefore to be distinguished from the Animal sense, and may be properly enough called a Sensation without Sense. And certainly such as this, is that sense observed in Zoophy●es or Plantanimals; as the sensitive Plant, the Boramets' or Vegetable Lamb of Tartary, Sponges, etc.  
We know, there are many Animals, that have both sense and motion; and yet have no brain, or Common sense, as Earthworms, Caterpillars, Silkworms, &c: and that there are some Natural Actions in us, which are performed without the influence or help of the brain. As Physicians, therefore, teach us to distinguish such actions Natural, from actions Animal: why may not we, with equal reason, distinguish the Feeling Natural, from the Feeling Animal; so as to refer one to the brain the other not.  
We know moreover, that it is one thing for a Muscle to be moved or contracted Spontaneously (as in Convulsion); and another, for it to be moved Voluntarily, or with various regulated contractions and relaxations, in order to the performance of some action intended, as Progression, or Apprehension. The Muscles, certainly, or Motory-Organs, are, in cramps and convulsions, moved spontaneously, upon their irritation by some acrimonious vapours, or other injurious cause; no otherwise than the body of a Fowl is moved, after the head is cut off. For as the body is tumbled up and down, and agitated by various convulsive motions of the feet and wings, yet such as are wholly confused and irregular, and of no effect either to progression or to apprehension, because the power and influence of the brain is extinguished; by the government and moderation whereof, those motions were formerly regulated either to progression, or flying: so in Convulsions, our Muscles are contracted, and our members variously agitated with irregular and ineffectual motions; because those motions depend upon a natural sense only, without the regulating influence of the Brain, which taketh no cognizance of the injuries done to the Muscles, nor of the sense which irritateth them.  
These things duly considered, Reason adviseth us, henceforth to lay aside that opinion of Des Cartes, and his disciple, Regius, (both great Philosophers, and in many other things worthy to be followed) that the influx of Animal spirits by the nerves, is necessary to the performance of all Natural Motions and actions done in the body: and to take up this more probable one of Dr. Harvey, that each Natural action is effected by the part doing it, merely in respect of a certain sense, whereby it feeleth what is troublesome and injurious to itself, and so is irritated to excite such motions of itself, as may conduce to its vindication; and this, without any influx or regiment of the Brain, or Common sense, at all.  
We might have added further, out of the same Dr. HARVET that all Motions in the body, are derivative from the Vital Influence of the Heart, and wholly dependent thereupon; because, no part is longer capable of this Natural sense, than while it is irradiated and enlivened by the Vital Spirits or blood flowing from the heart; for no part once mortified, i.e. no longer participant of the Vital influence, can have any sense, or be irritated to motion. Besides, it is not unreasonable to conceive, that the strength or Tone of each part doth mostly consist in its enjoying a due proportion of Vitality: and if that Tone or firmeness be vitiated or diminished (as soon it must, if deprived of that requisite influx), that part becomes languid, dull, and hardly capable of irritation But this noble speculation requires to be handled with more exactness, than the narrow limits of a short Digression will admit of: and we have already said more than enough to assert, that all parts of the body have a certain Natural sense of Feeling, distinct from the Animal, and wholly independent upon the Brain; which was the Problem proposed. ¶.    

OF RESPIRATION. Exercitation the Eighth.  
Of Respiration.  
THE Chain of Nature, 
Article  by which she connecteth various Operations conspiring to one and the same End, brings us in the next place to discourse of RESPIRATION; 
The Connexion of this Exercitation, to the precedent.  betwixt which and the Pulsation is a manifest affinity. For, these two Actions or Motions, as they are inservient to the conservation of the Lamp of Life, and the Generation of Vital Spirits; so do they both consist of a Dilatation and Contraction; the one of a Diastole and Systole of the Heart and Arteries, the other of a Diastole and Systole of the Breast and Lungs.  
Now this Affinity, hath given occasion to many Physicians to conceive the Diastole and Systole of the Lungs, to be Synchronical or coincident with the Diastole and Systole of the Heart; and to refer both their motions to the same cause and Original. But, They have grossly erred, in confounding things so manifestly different. For  
(1) There are many sorts of Animals, that have Hearts, 
The Disparity betwixt Respiration, and Pulsation; both as to their Times or periods, and as to their Uses.  but no Lungs. (2) The Dilatations and Contractions of the Heart, are clearly distinct from those of the Breast and Lungs; as is evident from hence, that they are not synchronical, i. e. made and terminated in the same periods and times; one complete Respiration taking up more time, then 4 or 5 Pulses: and this in all Animals that have both Heart and Lungs.  
(3) The Motion of the Heart and Arteries is much different from that of the Lungs, as to their Uses.  
For, First, if the Pulse and Respiration have one and the same Final cause, and that (as these men have assumed) the Arteries take in the ambient aer through the skin, at every Diastole; and exclude it again the same way, together with the Fuliginous Exhalations of the blood, in every systole; and that in the space of time intermediate betwixt each Diastole and Systole, they contain both the inspired aer, and exhalations: then must we renounce both the doctrine of our Master Galen, that in the arteries nothing is contained, but the blood; and our own experience, that confirms it.  
Secondly, if the Arteries were (as the Lungs are) filled with aer drawn in by their extremities, and that the quantity of aer attracted, were proportionate to the magnitude of each pulse, or to the greater or lesser dilatation of the arteries: then, if, while the pulse is great, the whole body were immerged into a bath of water or oil, it would necessarily follow, that the Pulse would become much smaller, or much slower; because it is highly difficult, if not wholly impossible, that the ambient aer should pass through the bath, into the pores of the skin, and so into the arteries.  
Thirdly, since all the Arteries, as well those that lie deep in the body, as those terminated in the skin, are moved with equal velocity, and at the same time; it is not possible, the ambient aer should as freely and swiftly pass through the habit of the body, into the profoundest arteries, as into those contiguous to the skin.  
Fourthly, it is not credible, that Whales, Dolphins, and other Cetaceous Animals, that have Respiration, can draw aer into their arteries, at every diastole, through so vasta mass of waters, as is from the bottom to the top of the sea.  
Fifthly, if in their systole, the Arteries expel the fuliginous exhalations of the blood, through the pores of the skin; why should they not expel also the vital spirits, that are far more subtle and fugitive, than those supposed Exhalations can be? Nature certainly hath made no such Colatory, as should retain the thinner spirits, and let the grosser fumes pass through. Nor is it yet sufficiently proved, that there are any such Fuliginous Exhalations generated in the heart and arteries, and afterward excluded partly by the Lungs, partly by the Arteries, in their Contractions; as are vulgarly believed. For, the blood suffereth only a simple agitation, or conquassation in the ventricles of the heart, and a propulsion in the arteries: and that it can produce such an abundance of sooty fumes from the blood, as Physicians have talked of; is not easy to conceive. Truth is, the blood, by reason of its heat and swift motion, doth emit some Halitus, or vapours (which streaming through the coats of the smaller arteries, are received and condensed into a thin limpid liquor by the Lymphducts) but is it therefore necessary, that it should emit Fuliginous exhalations? We confess also, that there is a certain thin Excrement of the blood and humours, which passeth through the habit of the body; but, that it should be discharged in thick clouds of exhalations, in every systole of the arteries, this is plainly impossible: because at that time the coats of the arteries are constringed and compressed, and there might be an easier egress for them, in the Diastoles, when the cavities of the arteries are dilated. So that among these many Arguments, there is not one, but doth clearly detect, and throughly refute the Error of those Men, who have confounded the Uses of the Arteries, and Lungs, of Pulsation and Respiration.  
This capital Error eschewed, we may the more safely progress to explicate the nature of Respiration, as a thing in sundry particulars distinct from Pulsation, though perchance instituted by Nature, as in some sort subservient to the vital Faculty. And, that we may proceed methodically, it is requisite we consider (1) the Manner of Respiration; (2) the Efficient Cause; and (3) the Final Cause, or Use of it.  

Concerning the First.  
Respiration [〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉] is an Action of the Breast and Lungs consisting of two contrary motions alternately successive, or of two parts, 
Respiration described.  viz. (1) Inspiration [〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉] in which the ambient aer is impelled into the Lungs and chest, at that time dilated: (2) Expiration [〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉] wherein the same aer is again expelled out of the Lungs and Chest, those parts spontaneously contracting or compressing themselves.  
Concerning the Inspiration, the grand Question is, Whether the Breast and Lungs are dilated, because they are filled and distended with the aer; as a bladder is distended by aer blown into it: or, Whether they receive in the aer, because they are dilated; as a pair of bellows is filled with aer, only because it is dilated or opened by external force?  
To solve this difficulty, in a word, we say, the Breast is first dilated, 
The Efficient Cause of Inspiration, is the Dilatation of the Breast, impelling the ambient 〈◊〉 into the Lungs.  before it can be filled with aer, and that Dilatation or heaving up of the breast is the cause of the airs rushing in at the mouth and nostrils, down the Aspera Arteria, or windpipe, into the Lungs. For, since there is no vacuity (at least not Coacervate one) in the world, no body can be moved out of its place, but the next body must give way, and the next to that likewise give back, till such a part of space as is adequate to the dimensions of the body first moved, be made to receive it, and the space which it abandoned, be again fully possessed by another body succeeding into it: we say, since this is necessary, it is manifest, that the aer next incumbent on, or contiguous unto, the Breast and Abdomen being urged and impelled by the breast, while that is dilated or expanded, is forced to give back, and press the aer next to it, which likewise drives back the next aer, until at length the compressed aer wanting room to retreat into, and endeavouring to avoid further compression, (its own Elater engaging it thereto) rusheth into the breast and there possesseth that room or part of space, which was left by the breast, when it began its motion. So that so much aer is impelled into the breast, as is driven out of its place by the superfice or outside of the breast, during its expansion or dilatation.  
As for the Attraction of Aer into the Lungs, ad fugam vacui; it is a mere dream; as well because all motion is by Impulsion, as because Nature doth not abhor vacuity primario or ex se, 
In Physiolog-Epiarro-Gassendo-Charltoniae, l●b. 1. cap. 5 pag. 40.  but only ex Accident, or in respect of the confluxibility of the insensible particles of Fluid bodies, as we have elsewhere amply demonstrated.  
And if there were any Cause to be found, that might blow the aer into the breast, as it is blown into a bladder, so as to distend it; or at least, if the aer could be conceived to enter into the breast spontaneously, or of its own accord, without impulsion, so as to force, or heave up the same: then indeed, would the Comparison betwixt the dilatation of the breast, and that of a Bladder, by wind blown violently into it, hold good, and we should not need to seek further. But, there being no such insufflating cause assignable; and it being ridiculous to imagine the aer should spontaneously move itself, so as to flow uncompelled into the cavity of the Chest (as is manifest not only in dead men, into whose breasts, though their mouths and nostrils are wide open, the aer doth not crowd itself: but also in living men, when they at their pleasure keep their breasts compressed, or hold their breath, as the vulgar phrase is), it seems much more reasonable to explain the reason of Inspiration, by that other similitude of the flux of aer into a pair of Bellows; there being no other difference betwixt the repletion of the Chest, and the repletion of a pair of Bellows, with aer, but only this; that the bellows are opened by an external force, and the Chest is dilated by an internal.  
And as for the Expiration, that is evidently from the compression of the breast and Lungs, 
And the cause of Expiration, is only the spontaneous contraction of the Breast.  which is the natural motion of Restitution For, the Dilatation being an action, whereby the parts of the Chest are distended into a position more large, than is natural to them; the Contraction seems to be nothing else, but a certain falling down or relaxation of the parts distended, whereby they spontaneously return to their natural position, and such as they hold in a dead body; and this not only in the Lungs, but also in the Diaphragme, which in dead bodies is not extended downward to the stomach and guts (as in inspiration) but riseth upward toward the Lungs and Heart. But if it be here demanded, whether Inspiration, or Expiration be first; we answer that it is necessary that the aer should be first inspired, before it can be exspired; and every ANIMAL dies Exspirando, in Expiration.   

Concerning the Second.  
The Enquiry is, By what cause the breast and Lungs are so dilated, 
The Dilatation of the Breast and Lungs, not from any Motive Faculty congenial to the Lungs.  as we have asserted? And this, indeed, is a Difficulty not so soon resolved, as proposed; for, besides the obscurity of the thing itself, we find ourselves benighted with the various opinions of Authors. Some will have, that the Lungs are endowed with a certain Faculty of Dil●ting themselves, and so elevating the whole breast: as the Heart hath a pulsifick faculty, by whose virtue the ventricles contract themselves in each Systole. And, hereupon was it, that Aristotle (the Author of this opinion) doth compare the Lungs to a pair of bellows, as if they did of themselves first attract the aer, and then emit it again. But, though it be true, that the Lungs are filled with aer, and emptied again, or elevated and depressed alternately, as bellows are; yet is it doubtful, whether (as the hand which moves the bellows, by opening and shutting them, is the cause both of the influx and efflux of the aer in them) there be not some other part of the Chest, besides the Lungs, which being first dilated and contracted, is the cause, why the Lungs are opened and shut? or more plainly, whether the expansion of the Lungs be from an ingenite Faculty? And, that the Lungs have no such Ingenite Motive-Faculty, is sufficiently manifest even from hence, that their motion is always conform to that of the Diaphragme, and from hence, that we can suppress, accelerate, or retard our respiration, as we please.  
Others derive the motion of the Lungs from the Heart, 
Nor from the impulse of the blood out of the heart into the Lungs.  or rather the blood expelled out of the right ventricle of the heart, through the Vena arteriosa into the Lungs, and so lifting them up. But this is erroneous, because (1) the efflux of the blood out of the right ventricle is caused by an ordinary motion purely natural to the heart; whereas (as we said even now) Respiration is sometimes arbitrary: (2) the cause of pulsation and Respiration would then be not only one and the same, but those motions also would agree in their times and periods; whereas scarce four, nay six, pulses are equal in time to one single Respiration: (3) the blood doth not stay long enough in the vessels of the Lungs▪ to keep them elevated all that while they are distended; but is in continual motion, and in a moment circulated by the Arteria venosa, into the left ventricle of the Heart: and where it is retarded in its course, by any misaffection either in the capillary vessels, or in the substance of the Lungs (as it many times happens, in the disease vulgarly called, the Rising of the Lights) it causeth extreme difficulty of breathing: (4) in great Apoplexies, while the pulse continueth good and regular, the Respiration many times ceaseth.  
Others will have it, that the Lungs borrow their motion from the Thorax, or 
Nor from the motion of the Muscles of the Thorax.  Chest containing them; but the reason which detain us from assenting thereto, is, that after the chest is cut quite open, the Lungs continue their motion for a good while, and strongly: which were impossible, if they derived their motion from the chest.  
Now it being evinced, that the Lungs are not moved either by themselves, 
But from the Diaphragme moved by a congenite Faculty.  or by the Heart, or by the Thorax▪ it remains, that they must be moved by some other part in the Breast, in which as in the first original, the motion of Inspiraiton doth begin: and this part seems to be no other, but the Diaphragme; and that for these reasons. (1) In wounds, or perforations of the breast, the Lungs instantly falling together, as it were close themselves (for some short space) while the Diaphragme is still elevated and depressed alternately, contracting and again relaxing the ends of the spuricus ribs, and cartilages to which it is annexed: whence it comes, that the aer rusheth violently into the cavity of the chest, and upon the elevation of the Diaphragme, is driven out again, through the wounds with impetuosity sufficient to blow out a candle. (2) Every man, in Inspiration, feels the Thorax to be dilated, and the whole Abdomen lifted up, and the ends of the lower ribs to be drawn inward: the Diaphragme being extended downward, with its middle part crowding down the stomach, liver and guts, and with its circumference or extreme parts contracting the ribs.  
(3) Allowing the Diaphragme to be the primum Movens, among all parts inservient to inspiration, we may easily understand, why the Respiration becomes more frequent and remiss, when the stomach is full, and when the Aer is made more dense, than ordinary, by fogs and thick exhalations. For, in the former case, the Diaphragme hath not room enough to expand itself downward, as it ought, and so is compelled to compensate the smallness of its motion, by the frequency of it; and in the latter, the Lungs are so prepossessed with gross vapours; as that they cannot admit much aer at a time; and therefore the Diaphragme is necessitated to repeat its motions so much the oftener. (4) In Apoplexies (unless they be fatal) though the Respiration be almost insensible, yet the motion of the Diaphragme is continued; as may be peroeived by the gentle motion of the Chest (5) Respiration is more perturbed and vitiated, by diseases of the Diaphragme, than by those of any other part of the breast: and it hath been observed by Veslingius that a steatoma grown upon even the carneous part of it, caused extreme difficulty of breathing. Now, these are the Reasons that have induced us to believe, that the Motion of Respiration gins in the Diaphragme; which being a kind of Muscle of a peculiar figure; 
Syntagm. An●tom. p. ii●.  substance, position, and action, may as well be conceived to be extended by virtue of a certain peculiar and ingenite Faculty, as the Heart is by a Pulsifick Faculty: so that we may conclude the same to be the prime and principal instrument of Respiration Natural or Gentle.  
We say Natural or Gentle, by contradistinction to Respiration Violent, 
Yet as well the Intercost all, as Pectoral Muscl●● are allowed to conspire with the Diaphragme, in Respiration violent and Arbitrary.  or Arbitrary. For, allowing of Galen's triple difference of Respiration, viz. Free and Gentle, violent, and more violent or sublime: we conceive the First to depend upon the Diaphragme alone; the Second, to require a concurrence of the Intercostal Muscles, of which the interior serve to contract, and the Exterior to dilate the Chest; and the last to be effected by the Diaphragme, Intercostal, and Pectoral Muscles, all being set a work, and combining together to the motion. And, as for Respiration voluntary, such as we can at pleasure suppress, accelerate, or retard; that is manifestly by the help of the Intercostal Muscles, there being no other instruments of Motion voluntary, but the Muscles; and no other Muscles immediately conducing to the contraction and dilatation of the breast, ex arbitrio nostro, but the Intercostal.   

Concerning the Third, viz.  
The Final Cause, or Use of Respiration.  
The most General opinion (to omit all others, as less considerable) is, 
The Final Cause of Respiration, not the Refrigeration of the Heart, or Vital Flame: but the subtiliation of the blood, which by the admistion of Aer, is made the more convenient Fuel for the Lamp of life, and matter of the Vital Spirits.  that the principal use of Respiration, is for the Refrigeration of the Heart. Which though very ancient and plausible, is rather merely Conjectural, than Areopagitical or demonstrative. For (1) AS aer overhot is injurious to the heart, so is aer over-cold: and as aer moderately cold is beneficial to the heart, when it is excessively heated; so is aer moderately hot, beneficial, when the heart is too much cooled. But, while the heart is in good temper, than the aer most agreeable to it, is neither hot, nor cold, but temperate. (2) It is inconsistent with the prudence of Nature, to make the natural heat of the heart so intense and excessive, as to require perpetual ventilation with cold aer: when it had been much easier for Her, to have kindled a more gentle fire there in at first, than to bring cold aer to the hearth with so much ado, to keep it in moderation ever after. And, in case that-Fire should chance, at any time, to grow less, or languish (as it often doth, in extreme cold aer, many men being frozen to death in Green-land, Russia, and other Northern Countries) what provision hath Nature made for the reaccension or instauration of it? (3) If it be only the Cold of the aer, that is beneficial to the heart; then, certainly, the Water, (which is much colder than the aer) would more conveniently satisfy that necessity in Fishes, which yet cannot live without aer. (4) In persons of cold and Leucophlegmatique constitutions, there would be no need at all of Respiration; especially in frosty weather, when the heart hath as much want of warmth, as of cold, and more too. We confess, indeed, that at such times, our Respiration is more slow and rare, and in the heat of Summer, more quick and frequent; as it is also in Fevers: but the reason hereof is, that in Summer, the blood being made hotter, is sooner subtiliated into spirits, and those spirits faster consumed and dissipated; and so requires more aer to promote the subtiliation and inflammability of its spiritual parts. So that it should seem, the Aer is required rather as an Excitement, than as an hindrance to the vital Flame. We say, for the Excitation, or Accension of the Flame of life, by subtiliating the blood, and making the inflammable parts thereof more convenient Fuel for the same vital Flame, and for the matter of the spirits, which being diffused through the whole body, serve to conserve and vivify all the parts; no otherwise than bellows conduce to the accension of flame in wood.  
For, as the Aer blown out of a bellows, doth promote the accension of fire, 
The same exemplified by the accension of flame in wood, by aer blown out of bellows.  in wood, or other combustible matter; not by reason of any Cold (for Contraries never generate each other) but by the subtlety of its particles, and the vehemence of its motion, in respect whereof it both dissipates the ashes, that hinder the ingress of the fire, and impells the particles of the fire into the pores of the wood; so as that they penetrating more deeply into the substance thereof, invade and kindle all the inflammable particles therein contained: so doth the Aer brought into the Lungs, and commixing itself with the blood circulating through them, insinuate itself, by the Arteria Venosa, into the left ventricle of the heart; and there partly by its subtlety, partly by its expansive motion, so conspire with the pulse of the heart, as to conduce to the rarefaction and subtiliation of the more thin and inflammable parts of the blood, that so they may be made both commodious fuel for the Fire burning in the heart, and also fit matter of the vital spirits. All the difference is, there are no Ashes made in the heart, the Flame thereof being more pure, than focal-fire, and subsisting in a matter as fine and subtle, as spirits of wine. Nor are there any sooty exhalations; such as arise from oil burned in a Lamp: but such a Flame is perpetually revived out of the blood in the heart, as is made by the purest spirits of wine set on fire.  
This Use of the Aer inspired, may be in some sort inferred from the very structure of the Lungs. 
And inferred from the structure of the Lungs.  For, to what purpose doth both the Vena arteriosa, and Arteria Venosa divide and disperse into so many branches and surcles, throughout the lobes of the Lungs; unless it be to convey the aer brought into them (out of the Bronchia, or pipes derived from the Aspera arteria) together with the blood, into the left ventricle of the heart, there to excite the vital flame? For, certain it is, from the structure of these vessels, that the Aer doth not arrive at and enter the heart, pure and sincere (as it ought to do, in case it were to refrigerate the heart) but mixed with the blood returning out of the Lungs: which is the reason, why in the dissections of living creatures, no aer is to be found in the Arteria venosa, being, before it comes thither, throughly commixed or confused with the blood. Nor can we force aer into the heart, through the Lungs of a dead body; because the motion of the blood is then ceased. And this we conceive to be the Principal End, or Use of Inspiration.  
As for that of Expiration, it seems to be no other but the explosion of the same aer formerly received; 
The Use of Expiration.  together with the Halitus, or vapours of the blood, that steam from it, while it is circulating through the Lungs. For, as to that Antique opinion, of the discharging of Fullginous Exhalations issuing from the heart; to the reasons by us formerly alleged to discredit the Generation of them, we shall subjoin two or three convincing one's, to disprove their Exclusion through the Lungs. (1) The motion of the blood out of the Lungs, by the Arteria Venosa, into the left ventricle of the Heart, being continual and strong; doth manifestly forbid any thing to come from the Heart, into the Lungs that way: and (2) the situation of the Valves in the same Arteria Venosa, doth as much. (3) That the Aer passing to the Heart, and the (supposed) Fuliginous exhalations issuing from the Heart, should be carried through one and the same vessel, by contrary motions; is insolent to Nature, and incompetent to the oeconomy of the body.  
And here we ask leave to propose a Problem. Certain it is, 
A Problem, of the Respiration of the Foetus, in the Mother's womb.  that the Foetus, while in the Mother's womb, doth receive nourishment (not by the Umbilical Vessels, for in them nothing is contained, but Blood, which is not the Aliment of the parts; and the Umbilical Vein serveth only to the Circulation of the blood, by bringing back to the heart, what the two Umbilical Arteries carried from it into the Placenta Uterina: but) by the Mouth, sucking in that milky liquor, wherein he swims: which Hypocrates long since, and Dr. Harvey of late, have undeniably proved. Now, this being so, doth it not seem necessary, that the Foetus should also have the use of Respiration? For, since all Suction is by Impulsion (as we have elsewhere at large demonstrated) being caused only by the pressure of the thing sucked, by the Aer impelled in round (as we lately expressed, in the cause of the influx of the aer into the Lungs, in Inspiration) certainly, without the help of aer, the Foetus cannot possibly suck in his nourishment. To this Reason (and we think it a weighty one) may be added, (1) the Authority of the Divine old Man, 
lib de Natur. pueri.  who in most express terms saith, 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 [viz. Foetibus] 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉, Puer ab ●lto respirat, & over & naribus. (2) that Chickens breathe in their shells (through which the aer hath a more difficult passage, than through the secundines) and Fishes in the water. And as the Chicken pipes within the shell not yet broken; so hath it been observed and recorded by sundry learned and authentical Writers, that Infants have been heard to cry in their Mother's wombs: which were impossible, unless they enjoyed the benefit of Respiration.  
(3) The posture of the Child in the womb seems to assert the same. For, as there is an ample space betwixt the coats of the Secundines, and the Child, to the end that a sufficient magazine of milk for his sustenance, might be stored up, and conserved therein; so is not that whole space filled up with that Liquor, but in the upper part there remains so much space unpossessed by any thing but Aer, as is sufficient for so gentle a Respiration, as the Infant hath need of: just as in the blunter end of an Egg, we perceive a certain empty space after the Hen hath sat upon it. And lest the Chorion should at any time be corrugated or shrieveled up together, and so straighten or compress either the Liquor, or the Infant; Nature hath affixed the same to the Placentae Uterina, to the end, that adhering to the bottom or upper part of the womb, it might hang fast, as an Apple hangs by its stem, or as our Globes of Glass are hung up by strings to the Ceiling of a room. So that the Chorion thus adhaering to the Placenta Vterina, which is fastened to the bottom of the womb, and the Amnios in like manner adhering to the Chorion, in the same upper part; and the lower part of each membrane being depressed by the weight of the Infant, and of the Humours contained in them: it thence comes to pass, that this Natural Machine both of the Child, and Membranes (though at first it were perfectly round, as the yolk of an Egg) is afterward made of an oval figure. For, though the Foetus, sitting incurved or bowed forward, as much as possible doth keep himself in a round figure, because of taking up the less room (for he sits with his legs crossed, his heels drawn up to his buttocks, his elbows resting on his knees, one hand held up close to his ear, the other to his cheek, for the more firm and easy sustentation of his head) yet, in that situation he hath need of a Mansion of an Oval Figure, that swimming in liquor, he might keep his head above water, and at his pleasure take in his nourishment by his mouth, and also inspire the temperate aer surrounding his head, in the void space of the Secundines; according to the opinion of Hypocrates newly recited. (4) Nor is the ingress of Aer into the womb impossible. For, albeit the mouth of the womb, in pregnant women, be shut up, so as to exclude one's finger, or (as others will have it) a small probe: yet is it not so sealed or luted up, as to exclude the Aer; as may be inferred from hence, that many Females have superfoe●ations, and more women (especially in this our moist Island) are troubled with the Fluor albus, all the time of their Gravidation; neither of which could be, unless the Cervix Uteri were pervious: For, if there may be an ingress for the seed of the male after a former Conception; and as free an egress for the matter of the Fluor albus, all the time of the gestation of the Foetus▪ then, doubtless, Hâc etiam penetret per cuncta meabilis Aer. These Reasons duly prepended, though it seems a Paradox, yet is it no light and vain Conjecture, that the Foetus doth respire in the womb, at least gently and placidly, and in proportion to the pulsation of his heart; which being calmly and softly moved (as are the hearts of Dormice and other Animals, that sleep all the winter) hath but a small necessity of Aer. However, reflecting upon the singular fabric of the vessels in the heart of an Infant unborn, which all Anatomists conceive made by the providence of Nature, only in defect of Respiration; as we proposed it a Problem, so we leave it to the consideration of wiser heads.  
Here also we may opportunely touch upon the Motion of the Brain, 
The Motion of the Brain dependent, not upon Respiration but upon the Pulsation of the Artsries.  which consisting (as that of the Lungs) of a Diastole and Systole, many have referred to the Inspiration and Expiration of Aer; as if the Brain were dilated for the admission of Aer, and contracted again for the exclusion of it. Whereas, indeed, this Motion doth not belong (1) to the substance of the Brain; for, that being very soft, tender, and delicate, seems uncapable of any such dilatation and compression. Nor (2) to the Membranes investing the brain; because, as Riolan observed in the head of a Sheep, the diastole and systole of the brain hath been continued long, after part of the skull and Membrans also were cut off. But only to the Arteries, (1) because the Motion of the brain is exactly coincident and concordant with that of the Arteries, as may be discerned by the touch, in the heads of Infants new born, and in large wounds of the skull. (2) Because the chief Pulsation is in the upper part of the Dura Mater, which is conspersed with store of Arteries ascending from the Plexus Arteriosus Mirabilis, and disseminating themselves upon it. (3) Because Waleus observed, that in some persons, who fell into extreme agonies, and swooning fits, upon great fractures of the skull, the motion of the brain ceased, and was begun again, as their Pulses recovered. (4) Of what Use should the inspired Aer be to the Brain? For Refrigeration, It cannot be; the temper of the brain being such, as seems to require rather Calefaction. And, as for the Generation of Animal spirits; Dr. Harvey hath upon good reasons made it doubtful, whether there be any such or not: and if there be, certainly they consist only of the purest and most subtle parts of the blood, and not of Aer, by the admistion of which they must needs become more crass and unfit for those noble uses, 
Encheirid. Anatom. lib. 4. c. 2.  to which they are consigned. And, therefore, Riolan said well; Nec spiritibus permiscetur Aer in Cerebro, quia debent esse subtilissim●; alioquin permixtione aeris cr●ssiores evaderent, nec tam celeriter in universum eorpus excurrerent per nervos.  
Nor must we here omit to touch upon the Secundary Uses of Respiration, 
The Secondary Uses of Respiration.  which are Manifold. For, it serveth (1) to the creation of the Voice (whether Articulate, as in Man; or Inarticulate, as in Bruits) the Lungs exploding the inspired aer, through the Aspera Arteria, with such impetuosity and swiftness, as that its frequent and strong Elisions in the head of the Larynx, the throat and other parts of the mouth, cause it to yield a found. (2) to the Distribution of the Chyle both out of the stomach and guts, through the venae Lacteae, into the grand Receptacle, and out of that Receptacle into the ductus Chyliferi: the middle part of the Diaphragme, in Inspiration, depressing the stomach and guts; and its two long carneous productions lying so immediately under the Receptacle, as that they cannot be distended, but they must at the same time also distend it, and so express the Chyle out of it. (3) to the Exclusion of the Excrements both of the Guts and Bladder; the depression of the Diaphragme together with the compression of the Abdomen, straightening and urging those parts. (4) too Smelling; the odours being brought into the Nostrils together with the inspired Aer. (5) to Coughing, Sternutation, Exscreation, and Emunction of the Nose; while the breath is driven forth with violence and suddenly. And (6) to assist the whole body in any strong and vehement motion; while, either the Inspiration being made gentle and small, and the breath kept in, the Muscles of the Abdomen and other parts are consequently stretched; and so we are the better enabled to lift up things of great weight, or to repel things making resistance by force of impulsion or otherwise: or, after a great inspiration, a vehement and sudden expiration succeeds, and then the Muscles are extended together with the like force, so as the Arms and Legs are strengthened either in giving a blow, or leaping, or other the like efforts, to which main force is required. And thus much of Respiration.    

OF THE LYMPHDUCTS. Exercitation the Ninth.  
Of the Lymphducts.  
AMong the new Discoveries made in the Microcosm, 
Article  by the Anatomists of this our age (wherein Nature seems to have rewarded the sweat and industry of her ingenious Votaries, 
The Lymphducts, a new and excellent Invention.  with the knowledge of sundry Secrets, which she wholly concealed from our Predecessors) These vessels are not the least: nor can you have a complete History of the Oeconomy of Nature in an Animal, without assuming both them, and the Liquor they contain, into particular consideration.  
To whom the Honour of their Invention doth belong, 
To whom the honour of their Discovery is to be ascribed.  is yet in dispute. For, though that most diligent and perspicacious Anatomist, Thom: Bartholinus, be the man, who first wrote of them; and He challengeth the glory of their discovery wholly to Himself: yet is it well known, that our Country man, Dr. jolive (a person of singular dexterity, and admirable felicity, in dissection of all sorts of Animals, as well living, as dead) had discovered and mentioned them to many Physicians of best note, and among the rest particularly to that eminent Master in Anatomy, Dr. Glisson (who makes grateful acknowledgement thereof, in his most elaborate and judicious Book, de Anatom. Hepatis) more than a whole year, before Bartholine wrote his Treatise particularly concerning them. So that it being improbable Dr. jolive should borrow the notice of these Water-vessels from Bartholine; and as improbable, on the otherside, that Bartholine should receive the first Hint of them from Dr. jolive: it seems equitable the Honour of this invention should be divided betwixt Them, as Men, whom good Fortune, conspiring with their industry, might haply bring to the investigation of the same thing, near about the same time; notwithstanding they were divided by so large a distance, as is betwixt England and Denmark, and held no commerce each with other by Letters, or otherwise. But whoever was the Inventor, certain it is the Invention itself is of admirable advantage to the Republic of Physic: and therefore, we shall briefly recite the sum of what hath been written concerning their Description, their Origination, their Insertion, and their Uses.  
The Lymphducts are certain Whitish Vessels, 
Their Description.  in many places of the body running along close upon the veins, and sometimes embracing them in various circles, as the surcles of the Vine twine about the branches of an Elm, consisting of a very thin and transparent membranous substance, not much unlike a spider's web; in Figure for the most part roundish; in magnitude seldom exceeding a Raven's quill●; furnished with sundry tender valves▪ and containing a Liquor thin, insipid, and for the most part whitish, but sometimes tinged either with blood, or with a yellowish colour.  
Of these are two sorts; 
Differences.  some accompanying the larger veins in the Limbs, or exterior parts; and others associating themselves with the veins in the Abdomen, especially with the Vena Fortae, the Iliacal veins, those diffeminated upon the Testicles in both sexes, and upon the bottom of the womb in Females.  
Accordingly, 
Origination.  their Origine is twofold; for those in the Abdomen arise either from the Liver, or from the Bladder of the Gall, or Capsula communis: and those in the Limbs, have their original from those parts; but, whether from the capillary veins, or from the capillary Arteries, or from the extremities of the Nerves, is not yet determined. Only we have the late observations of Olaus Ra●beak (Physician to Queen Christina of Sueden) to attest, that they arise almost from all parts; he having found them also in the Lungs, Mediastinum, Heart, suspensory ligament of the Liver, stomach, spleen, loins and sundry other parts.  
Their Insertion likewise is twofold. 
Insertion.  For, those in the Abdomen are all terminated in the grand Receptacle of the Chyle, into which as into a cistern, they infuse that thin liquor, which they carry in their pipes; that so the same being there commixed with the Chyle, may be conveyed along with it, through the Lacteae Thoracicae, into the subclavian vein. And those above the Diaphragme, or such as arise from the Limbs, are inserted into the External jugular Veins, into which they disembogue their several rivulets. Wherefore they have no common Trunk, but (like several Springs of water) rising up here and there from divers parts, they all tend into two large channels, viz. the Receptacle of the Chyle, and the Vena Axillaris, that their streams may all meet in the common Ocean of the Heart.  
As for their Situation and Progress, it is thus. In the Arms, 
Situation and Progress.  they creep up by the side of the Vena Brachialis, to which they are firmly connected, and so ascend together with it to the Vena Axillaris, into which they open themselves with a small inlet, or Orifice, that is guarded with a valve, set there by Nature, to prevent the reflux of the liquor out of the Axillary vein. And, from the Thighs, many in like manner climb up in the company of the Crural and Iliacal veins, which they encircle in some places more closely, in others more laxely; and in this manner they mount up to the Mesentery, where together with the small branches of the Vena Portae, they are terminated. Again, those issuing from the Liver, or Bladder of the Gall, do also descend in company of the Vena Portae, to the middle Glandule of the Mesentery, and are therein terminated. But, if with a more curious eye you trace these proceeding from the Liver, up to their very original; you may perceive them to enter the Capsula Communis, of the Vena Portae; and therein so to lose themselves, as that you cannot discern their progress from thence: yet it is probable, that being included in the same Capsula Communis, they follow the distribution of the same, and never stray from it into the Parenchyma of the Liver; because, if they did, how comes it, that they are not where to be found in the parenchyma, no not in that part of it, where the Capsula Communis is?  
Concerning the Liquor they contain, there are two Difficulties, viz. (1) Whence they receive it? (2) Why they return it into the Receptacle of the Chyle, and into the Heart?  
The Former is solved, by saying, that the liquor is derived partly from the Arteries, 
Liquor deduced partly from the Arteries, and  partly from the Nerves. That the Arteries have some share in bringing that mild and thin Liquor into the Lymphducts, may be argued thus. The blood, being by the Vital Heat and Motion, agitated in the Arteries, doth necessarily diffuse abundance of Vapours into those parts, into which it is immitted; and this so much the more, because those vapours are repressed and kept in, by the thickness of the coats of the greater Arteries, until they are driven into the smaller arteries, through whose thinner coats they more easily transpire. And these vapours thus dispersed, ●re for the most part retained and re-collected by the Fibrous and Membranous parts, and by that means condensed into a Liquor, which makes one part of that Humour which the Lymphducts carry away. For, we are not to conceive, that that Liquor was preexistent in the Arteries, under the same form it afterward obtains in the Lymphducts; and that being protruded together with the blood out of the Arteries into the substance of the parts, it is in those parts separated from the blood, by any kind of Percolation, as the Urine is in the Kidneys: because there are in all parts Veins answering to the Arteries, and those ample enough to export whatever liquor is by them imported: nor can any reason be given, why that watery humour should be at all separated from the blood; seeing it is no Excrement of the blood, though it may be accounted an Excrement of the parts, from which immediately it is immitted into the Lymphducts. No Excrement of the blood, because it is again brought into the blood; and Nature useth not to lose her labour, or to separate things each from other, on purpose to mix them again afterward.  
Secondly, that the Nerves also contribute some part of this Liquor to the Lymphducts, 
Partly from the Nerves.  may be inferred from hence; (1) that whatsoever Liquor ariseth from vapours condensed, is perfectly pure, thin, and transparent: but this liquor is not so, and therefore it is necessary some other Humour should be admixed to it, which gives it a greater thickness, than a simple distilled water usually hath. For, this whole liquor is more dense, and less diaphanous, and sometimes white like milk, sometimes tincted with yellow, and sometimes with blood, like water wherein raw Flesh hath been washed. (2) It is an opinion highly agreeable with Reason, that the thicker part of the Liquor found in these Water-conduits, is the Vehicle of the Succus Nutritius, which being dispensed from the brain and spinal Marrow, to all parts for their nourishment, by the Nerves, is assimilated into their substance, leaving its thinner part (which before served to promote and facilitate its distribution through the slender passages of the Nerves) to be infused into the Lymphducts, which return it into the blood, for a double use, viz.  
First, to prevent the Coagulation of the blood, to which otherwise it would be strongly inclined. 
Uses of that Liquor.  Secondly, to promote the Mication of the blood; for this thin liquor, being formerly advanced to the state of Volatility, or exhalation: it easily united to the Vital blood, and doth as easily advance the mication of it.  
But, what we here say, of the derivation of one part of this Liquor from the Nerves, will be more illustrated by what follows, concerning the dispensation of the nourishment by the Nerves.   

OF THE DISTRIBUTION OF THE NOURISHMENT THROUGH THE NERVES. Exercitation the Tenth.  
Of the Distribution of the Nourishment through the Nervs.  
IN one of our precedent Discourses (as you may please to remember) we denied the Blood to be the Adequate Aliment of the Nervous, 
Article  Fibrous, 
That the Nervs are the vessels carrying the Nutritive juice to the parts; argued  and Membranous parts of the body; and transferred that noble office upon a certain milder and sweeter juice, congenerous to that spermatical Matter, of which those parts are first made up: Lest therefore, we should defraud your curiosity of such further satisfaction, as this new and paradoxical (yet most reasonable) opinion requires; we must no longer omit to explain (at least according to what light the excellent Dr. Glisson hath given, in so obscure an Argument) From whence, and by what vessels, the Nutritive juice is distributed to all parts of the body.  
The Thesis is, that the proper and adequate Nutriment of the Parts, is derived to them from the Brain and Spinal Marrow, by the Nervs: and the Reasons asserting it, are these.  
(1) In the Palsy, it is observed, 
from the Atrophy, or decay of nutrition in parts affected with the Palsy, and whose Nervs have been wounded.  that the parts resolved do at first appear somewhat tumid or swollen, by reason of the laxity of their Fibres, and the easy afflux of blood unto them. And yet it is manifest, that swelling doth not arise from the true and genuine Nourishment of those parts; because afterward they by little and little pine away, to extreme leanness, notwithstanding the blood floweth as freely and plentifully to them then, as before. A pregnant argument, that the vessels, by which they ought to be supplied with nourishment, are obstructed; which vessels, certainly, can be no other but the Nervs, because both Arteries and veins are wholly exempt from any impeachment, in this Disease; and the Nervs alone fail of performing their office, as they ought.  
This may be confirmed by an observation of our own. A certain woman having a Nerv pricked by an unskilful Chirurgeon, as he was letting her blood in the right arm, was at first surprised with Convulsions of that Arm; and those ceasing, there ensued so great an Atrophy of that member, as nothing now (for the woman is yet living) remains of it but skin and bones: which extreme extenuation, doubtless, is to be referred to the want of passage for the Succus Nutritius, through the principal Nerv in the Arm; 
from the beneficial use of Cephalique Emplastres in Consumptions from ulcerated Lungs.  no such accident (but an Aneurisme) usually following upon the incision of an Artery.  
(2) In a Phthisis, or Consumption from ulcerated Lungs, Cephalique Emplastres (though composed of hearing and drying ingredients, and in that respect seeming very incompetent for such a Disease) are found by experience to be very beneficial to the sick; and that, not only because they stop the defluxion of humours from the head upon the Lungs: but also (and chief) because they warm and corroborate the Brain and Nervs, and so promote the Nutrition of the Parts. Which effect cannot be expected from their Heat and Dryness, but from some comfortable influence transmitted to the Nervs, by which they are strengthened and made fit for the performance of their office, viz. the conveying the nourishment from the brain to the parts.  
(3) As those persons are inclined to Leanness, who abound with blood; 
From the Fatness of men endowed with large, open, spongy and moist nerves  so are those inclined to grow Fat, who have large, moist, open, and spongy Nervs; for, such Nervs afford much Aliment, and distribute it easily.  
(4) It is commonly observed, that from wounds of the joints and Nervs, 
From the roscid humour exstilling from wounds of the joints and sinews.  there distils a certain roscid Humour, not much unlike the white of an Egg; which being not likely to come from either the Arteries or veins, in respect they carry nothing but blood; why may we not believe it to drop out of the Nervs? Also in such wounds, in issues, in hollow Teeth, etc. there grow up frequently certain fleshy Excrescences, or Proud Flesh; which being exceeding sensible, and subject to acute pain upon the least touch, cannot but have a very near relation to the Nervs: and blood certainly is very unapt to produce such Excrescences, to the Generation of which some matter analogous to the sperm is necessarily required.  
(5) The same may be said also of Wens and Scrofulous Tumours, which seem to derive their Seminal Matter from the dew or G●eet of the Nerves, 
From the Material Principle of Wens and Scrofulous Tumours.  and not from any humour effused out of the Arteries or veins; blood being a liquor partaking of too much Asperity and Acrimony, to be the material Principle of such Tumours: besides, we have the testimony of our sense, that the rudiments of such Tumours, are like Eggs included in a membranous film, which contains a humour resembling the white of an Egg, but nothing like blood. Moreover, these Tumours frequently tend to some kind of Formation, though but an imperfect one; producing sometimes a mass or lump of Flesh, sometimes a Worm, or other (such Monster; which is a strong Argument, that their primitive Matter is not blood, but a certain juice much milder and sweeter, and brought to the parts in which they are generated, by the Nervs.  
(6) This Opinion is further confirmed by the Matter of the Seed, and the Manner of its preparation in the Testicles. 
From the Matter of the seed▪ and the Manner of its praeparation in the Testicles.  For, the Seed seems to be generated, not of the blood (as hath been vulgarly believed) but of a matter much sweeter and more generous, brought into the Seminary vessels, from the brain, by the Nervs: forasmuch as the Nervs are both more copiously and more deeply disseminated into the parenchymas of the Testicles, than either the Arteries, or the veins; which is the reason, why their inward substance is white, not red. Again, their proper Coat appears to be nothing else, but a certain expansion of the Nervs inserted into them; from which Coat many small Nervs are on all parts derived to the middle of the Testicles, where meeting together, they make the long Nervous vessel, that manifestly exonerateth itself into the Channel of the Epididymis, as may be plainly seen in the stones of a Horse, Bull, Boar, or other large Animal. As for the veins of the Testicles, they serve only to export the blood imported by the Arteries: and the Arteries themselves, though they variously diffuse themselves round about the Testicles; and accompanying the Nervs, tend in divers places from the inward coat, to the Ductus Seminalis (situate in the very middle of the Testicle) and are connected thereunto; yet they rarely disperse any branches, until, reflecting from that channel, they have begun their progress back again toward the Circumference of the Testicle. But, there they send out some surcles to the outside of the Testicle; to the end that, those capillary veins, opening themselves into the substance of the Testicle, may the more easily receive the blood effused out of the Arteries, and so carry it off again. Because, that blood, if left there, would soon obstruct the parenchymas of the Testicles, and disturb the praeparation of the seed. Yet these Arteries no where insinuate themselves into the Nervous, or Seminal Channel, or infuse the least drop of blood into them: So that it is more than probable; they serve rather for the vivification of the Testicles, by bringing the vital blood and spirits into them, than for the importation of the Seminal Matter. Now, the Nervs implanted in the Testicles, cannot be in order to their Motion, because they have none that is voluntary; nor is there any need of them, as to sensation: and therefore it is more credible, that their Use is only to bring in some certain Liquor, for the making of seed. Furthermore, the Testicles are furnished with many Lymphducts, which could be of little Use unto them, unless there were some other vessels present also, by which that generous Liquor is brought in, whose thinner and superfluous part those Lymphducts are framed to export. Add to this, that the seed is a liquor much more noble and Ambrosiac; than the blood; as is evident even from hence, that a small expense of seed doth more exhaust the spirits, than the loss of twenty times so much blood. Which doubtless, is the reason, why Heaviness and dejection of spirit, do always ensue after the delights of Venus; and it hath been observed, that in men excessively addicted to women, the Brain itself is not only much debilitated, but made also lax, thin, and watery. The Gout-likewise is generally an Attendant of immoderate venery; because the joints and nervous parts being much debilitated, and the roscid and Unctuous Liquor of the Nervs, deprived of its milder and sweeter part, the Succus Nutritius becomes too thin and sharp, and so is more expeditely discharged upon the joints.  
(7) From the Extremities of broken Bones, 
from the Glutinous ma●ter issuing from the ends of broken bones, and cementing them together again.  there sweats forth a certain Glutinous substance, very beneficial toward the uniting and cementing them together again: which liquor cannot proceed from the Arteries, whose office is only to convey the blood (a liquor vastly different from this Glue): and since besides them, and the Nervs, there is no vessel yet found out, that carries any humour from the Centre to the circumference of the body; it is very reasonable to conceive, that this Glue is derived from the Nervs.  
(8) The White of Eggs is brought into the womb of the Hen, by the Nervs. For, it hath no resemblance at all to blood; nor can it be generated of blood, unless by way of separation, but there can be no separation made in that part, in respect it is wholly destitute of any Parenchyma, which is absolutely necessary to the separation of any two Humours one from the other. Whereas the secretion of the Succus Nutritius brought by the Nervs, seems to want no parenchymas, and may be effected in parts the most bloodless. And that such a Secretion of the Succus Nutritius is made in the womb, is manifest from the great number of Lymphducts returning from thence, which Nature had never ordained in that place, unless it were to export the thinner and superfluous part of the Succus Nutritius brought to the womb by the Nerves. So that the very Lymphducts seem to teach us, that the Succus Nutritius is derived into the womb by the Nerves; and that the watery part thereof being protruded into the Lymphducts, the more unctuous and profitable is transmitted into the cavity of the womb, there to make the White of the Egg.  
(1) In the Rickets there is generally observed an Inequality of Nutrition, 
From the Unequal nourishment of some part, in that Rickets.  which (according to the most of probability) proceeds from the less aptitude of some Nerves, to carry the nourishment, than of others. For, that Disease seems to be seated originally and principally in the Spinal Marrow without the skull, and in the Nerves thence propagated: and therefore those Nerves must be more weak, languid, and unfit to transmit the Succus Nutritius, than such as arise from the Brain, or Marrow within the skull. And hence is it, doubtless, that the Head, Face, and Viscera of the Abdomen (all which derive their Nerves from the Marrow within the skull) grow excessively great: while the Arms and Legs become lean, flaccid, and enervate, as being supplied with nourishment by Nerves, issuing from the Spinal Marrow without the skull. Moreover, because it sometimes happens, that some one particular branch of this or that Nerve, is more debilitated, than the rest; thence it comes, that one part of a Limb is better supplied with nourishment, than the other; and so, by that unequal Nutrition of its parts, the whole member grows crooked. And these are (among many others) the chief Arguments, that have persuaded us, that the Nourishment of the parts is brought to them by the Nerves.  
Among the Difficulties encumbering this opinion, 
Three grand Difficulties, troubling this opinion.  there are 3 that especially deserve consideration, viz.  
(1) That in the Nerves no passages or cavities can be discerned, through which the Succus Nutritius may be conveyed.  
(2) That in the dissection of Animals alive, and the application of a ligature to any Nerve, no swelling can be observed to arise on either side the Ligature: and upon cutting off a Nerve, very little or none at all of this supposed Liquor can be discerned to distil from either end; contrary to what happeneth in the binding and cutting off any other vessel.  
(3) No such Liquor hath yet been found in the Nerves of bodies dissected.  
And yet these Difficulties are not weighty enough to counterbalance the Reason formerly alleged; forasmuch as they may be easily solved, by Answering to the  
First; 
Solution of the First, asserting the possibility of the flux of the Nutritive juice, through the Nervs, notwithstanding no manifest Hollowness can be discerned in them.  that though no manifest hollowness be discernible in the Nerves (such as is in Arteries and Veins) yet is it not impossible, but the supposed Succus Nutritius may distil gently through them. For, it is well known by the experiment of lowing the Spinal Marrow, or any Nerve in water; that the Nerves are made up of many small Fibrous, Filaments, or threads coh●ering together, with a soft medullary substance betwixt them: much like the Indian Canes, which, though in the cortex so hard and compact, as to yield fire upon percussion with a Tobacco-pipe, and as solid within as many sorts of wood; being yet composed of many small and long Filaments, with small perforations betwixt them, are pervious from one end to the other, so as a man may without much difficulty blow his spittle quite through them. Likewise, in the leaves of plants, there shoots up a certain small Nervous rib, arising from the Foot-stalke, by which they are fastened to the branch; and without which nothing of nourishment can be brought to them. This little rib running up in the middle, sends forth various lesser surcles or threads equally to all parts of the leaf, so as the whole is thereby equally nourished. And yet, if you cut off this rib, or any one branch of it, you shall discover none the smallest cavity or hollowness therein, nor any drop of juice issuing out of it, unless in the Sowthistle, Esula, Celendine, and some few other plants, which emit either a milky, or a yellowish juice, which certainly is their nourishment. And though other plants yield not, upon cutting of their leaves, the like juice; yet most certain it is, they are nourished with some kind of juice or other, derived to them by their Foot-stalks: So that we can perceive no such absolute necessity of any manifest cavity in their small ribs, for the dispensation of their nourishing juice, as this Objection seems to import; especially when we consider, that the Motion of the Succus Nutritius in those slender Filaments or threads, is very gentle, slow, and insensible; not rapid, or Violent, as the motion of the blood in the Arteries and Veins of Animals. Now, since our sense is witness, that liquor may be transmitted through a Fire-cane though sufficiently solid and compact; and our Reason assureth, that the Nutritive juice of Plants is distributed to all parts of the leaves, through the Foot-stalk, and little Rib running up in the middle of each leaf, though we can discern no manifest passages, or channels, through which it flows: Why may not the nourishment of Animals be, in like manner, dispensed to the parts, through the Nerves, notwithstanding they appear destitute of any conspicuous hollowness? But yet some Nerves there are not so impervious, but they admit a small style or probe into them; in which number are the Optic and Odoratory Nerves: and though the rest have not the like visible hollowness, yet reflecting upon this, that all the Nerves are framed for the performance of some one Common Office, it is not unreasonable to conceive, that all of them are perforated more or less, so as to be capable of conveying the Succus Nutritius. This may be in good part inferred even from hence, that the Apoplexy often ends in a Palsy; in which case all Physicians grant, that the Humour oppressing and obstructing the Brain, is discharged thence upon the Spinal Marrow, and Nerves affected; which could not be, unless the Nerves were capable of being obstructed by the Humour protruded or impelled into them.  
You will reply, perhaps; that they are capable, indeed, of the influx of Animal Spirits, unless their originals chance to be obstructed, as in the case of the Palsy: but, as for any Liquor, or Humour (of far less subtlety, than those Spirits) it is impossible they should admit it into them. And we may return, that the supposed Animal Spirits (nor, intruth, the Vital ones) are any where to be found in the whole body, pure or sincere, and without mixture; and therefore, if the Nerves were framed for the reception of any matter pure and distinct from all others, certainly that matter must be of a grosser substance, than simple and abstracted Spirits.  
Furthermore, that there are small Channels in the Nerves, may be perceived by their Compression in our limbs, as when we have long fate upon a hard seat, or otherwise straightened our sinews; for, in that case, we feel a certain stupor, or Numbness (the vulgar say, their limbs are asleep) in that part, to which the compressed Nerves are prolonged: a certain document, that the free passage of some matter through them, is at that time intercepted; and the compression being removed, there instantly ensues a kind or troublesome Tingling or Pricking, as if the part were pierced with needls; and this only because what was arrested and intercepted there, gins again its former liberty of motion. These things duly weighed, we may lawfully conclude▪ that it is not sufficiently 〈◊〉, that the Nerves are impenetrable by the Succus Nutritius, only because they have no manifest cavity.  
Second; that in the dissection of an Animal alive, 
Solution of the Second, yielding the reason, why no swelling ariseth in a Nerv, when bound with a Ligature, in a living Animal.  it generally happens that by reason of the extreme striving and agony of the poor tortured Creature, before the dissector can come, either to apply a ligature unto, or to cut a Nerve; all the Liquor contained therein is squeezed forth into the part, wherein the Nerve is terminated; so that no wonder, if there appears neither swelling on either side of the ligature, nor any exstillation of liquor from the ends of the Nerve cut off. And this Violent straining of the Nerves in dying Animals, and the squeezing of the Liquor contained in them, into the parts to which they are inserted; seems to be the Cause, why that Lympheduct, which corresponds to the Nerve bound or cut, is found more full and distended, than ordinary, as hath been of late frequently observed. And yet we have been assured by judicious and credible persons, that they have seen no small quantity of the Nutritive juice exstilling out of the Nervous Chord of the Thigh in a man; and pressed some of it out of the Axillary Chord, in Dogs.  
Third, as to the Second; adding withal, that (besides what hath been said, 
Solution of the Third, showing the reason, why the Succus Nutritius is not found in the nerves of dead bodies dissected.  of the cutting of the Nervous Fibres in divers plants, without effusion of the least drop of their Alimentary juice) the Motion of the Succus Nutritius through the Nervs, is neither Continual, nor impetuous, but by intervals, and gentle, so as not to be perceived: and that all of it being forced into the parts, by reason of the strong Contention or straining of the Nervs, in the very agony of death; and all impulsion of humours in the body, ceasing after death; it cannot seem strange, that none of the Succus Nutritius can be found in the Nervs of bodies dissected after death.  
These Grand Objections thus solved, it remains that we inquire; (1) What is the Principium Elaboratioms of the Succus Nutritius, or where it is praepared: (2) What is the Principium Dispensationis of it, or whence it is immediately infused into the Nervs, which convey it to the parts: (3) By what vessels it is imported into that principium Dispensationis: (4) What kind of Motion it hath in the distributing Nervs: and (5) What is the Cause of that Motion.  
Concerning the First, 
What is the Principium Elaborationis of the Nutritive juice; viz. the Glandules of the Mesentery, of the Loins, and the Thymus.  viz. the Parts wherein the Succus Nutritius is prepared, immediately before it is imbibed by the Nervs; there is good reason for us to believe, that this work is effected in the Glandules of the M●sentery, in the Three Glandules of the Loins, and in the Thymus, or Glandule in the Thorax. Which opinion that we may the better explain, it is requisite we make a short Digression concerning the Differences and Uses of the Glandules, according to the observations, and consequent Conjectures of Dr. Glisson, and Dr. Wharton.  
Of the Glandules in the body, there seem to be 3 sorts (respectively to the Nervs) whereof some be inservient to Excretion, some to Reduction, and some to Nutrition. For, though it be most true, that the Common office of all the Glandules, is Secernere, to make some separation; yet is it no less true, that that separation is various, as tending to Excretion in some, in others to Reduction, and in others to Nutrition; and the Matter itself, which is separated by those divers ways of Secretion, being likewise various, the first sort being a mere Excrement; the Second, an Excrement only in relation to some parts, but profitable in relation to others, and therefore not to be excluded, but retained; and the last, the true Succus Nutritius.  
Under the First Classis of those Glandules, are comprehended the Testicles, the Prostates, the Vesiculae Seminales, the Paps in women, and the Glandulae Maxillares, or spitting Glandules under the Tongue: all which are furnished with a peculiar Excretory vessel, by which they discharge and avoid some superfluous matter brought into them by the Nervs.  
To the Second (inservient to the secretion of a humour, and the reduction of it into the veins afterward) belong the Glandulae Renales, or Deputy Kidneys, the Glandules near the Fundament, those adjacent to the Oesophagus, the Parotides, Axillary, Inguinal, etc. Glandules. All which receive from the Nervs, a certain humour more rough and acrimonious (and approaching to the nature of the blood) than is agreeable with the Succus Nutritius; and therefore the Nervs, by the help of these Glandules discharge themselves of it, and retain only the more sweet, mild and profitable juice. But, because the Humour, thus rejected by the Nervs, hath some affinity to the blood, and in respect of its thinness is commodious for the more easy transportation of the blood, through the narrow meanders of the veins: therefore is it not excluded out of the body, as an absolute Excrement, but imbibed by the Glandules adjacent to the veins, and by them imported into the veins. Which seems to be the most satisfactory reason, that hath hitherto been given, why such Glandules are placed, for the most part, near to the greater Divisions of the Nervs and veins; viz. that they may the more conveniently receive the humour effused out of the Nervs, and deliver it again into the veins.  
And to the Last (inservient to the Praeparation of the true Succus Nutritius) belong the Glandules of the Mesentery, the 3 Glandules of the 〈◊〉 and the Thymus, or single Glandule in the Chest, near the Ductus Lactcus Thoracicus, and in Brutes called the Sweetbread. For, (1) as to the Glandules of the Mesentery; Anatome assureth us, that a great multitude of the Venae Lacteae tend unto them, and are in them distributed into surcles extremely small; and that other small branches (or rather roots of milky veins take their beginning in the same Glandules, and progressing from thence, make a second sort or race of venae lacteae, as we have more particularly declared before, in the 2d Art. of the 3d Exercit. Now, to what end hath Nature made these two kinds of Venae Lacteae, one sort to import the Chyle into these Glands, and the other to export it? unless it be, that the Chyle should either suffer some Alteration, or be separated from some Humour, in these Glandules? Alteration it suffers none; because it is carried off again in the same form, as it was brought in. And, therefore, it remains probable, that it is brought into the Glandules, only that it might be separated from some parts less agreeable with the nature of pure nourishment. Now, what should the Humour be, that is thus to be separated? An absolute Excrement it cannot be, because these Glandules have no peculiar Excretory vessels, as all parts inservient to any Excretion have. Nor is it like that matter, which is reduced into the veins, by the Reductory Glandules: for, if it were such, it would need no such separation at all, the rest of the Chyle soon after flowing into the subclavian vein, and it being easy for Nature to have contrived, that the chyle brought into these Glandules, might have accompanied the rest in that journey, without any intermediate Secretion. This considered, it is reasonable to conceive, that the Liquor separated from the Chyle, in these Glandules, doth not belong either to the First, or Second sort of Matter (viz. the absolute Excrement, and the Excrement Relative) formerly mentioned; but is the true Succus Nutritius. Which being granted, it is not difficult to explore, by what vessels this Succus Nutritius is from thence carried away. For, since it cannot be thence exported by any peculiar vessels, nor by veins; it must be by the Nervs. (2) As for the Three Glandulae Lumbares; it is probable, They also are official to the Nervs, in the same way; and that for two important Reasons. First, because they are furnished with Venae Lacteae of both sorts, some tending to them, and others propagated from them, and exonerating themselves into the Common Receptacle: in all points like the Glandules of the Mesentery. Secondly, because in such Animals, as have the Glandules of the Mesentery very large, these Glandulae Lumbares are either very small, or wholly deficient; and in men, in whom the Glandules of the Mesentery are but small, the Lumbares are great: an undeniable argument, that the same office is common to both sorts, and that the exility of those is supplied by the amplitude of these. And (3) the Thymus also seems to be a Nutritious Glandule. For, in Infants, and other Animals new born (at which time, they grow much, and so require the more abundant nourishment) the magnitude of this Glandule doth exceed that of any other in the whole body: but, in old men (who daily go down the hill of life, and so have less need of nourishment in such abundance) it dwindle's away to a smallness many times scarce discernible. Again, this Glandule hath no Excretory vessel, nor (like other greater Reducing Glandules) any hollowness within; and therefore, we may well list it in the number of Nutritious Glandules. Add also, that it is white, soft, and very sweet, and in substance resembling the Glandules of the Paps: so that in probability, as the paps serve to prepare nourishment for the infant, ab extrà; the Thymus supplieth him with nourishment, ab intrà; receiving the same, perhaps our of the Ductus Lacteus in the Thorax, which in its approach to the Thymus, is usually divided into two streams or rivulets. And these are the reasons, upon which we conclude, that the Nerves take in some of the Succus Nutritius, out of each of these Glandules mentioned, whose use seems to be, to separate the same from the less Alimentary parts of the Chyle.  
Concerning the Second thing enquired, 
What is the Principium Dispensationis of the same; viz. the Brain and Spinal Morrow.  viz. what is the Prineipium Dispensationis, whence the Succus Nutritius is immediately immitted into the Nervs, which convey it to the parts requiring nourishment? We say, that the Brain and Spinal Marrow seem to have the best title to that office, of all other parts, in respect that all the Nervs desuming their original from, and having their extremities or roots immediately fastened unto either the Brain, or Spinal Marrow, the Nutritive juice may commodiously and easily from thence dissill down upon all parts of the body; according to their particular conditions and necessities.  
Concerning the Third; 
What are the Vessels importing the Nutritive juice into the Brain and Spinal Marrow; viz. the Nerves, and particularly those of the sixth Conjugation of the brain.  viz. By what vessels the same Nutritive Liquor, is brought into the brain and Spinal Marrow? We say, By the Nerves, and particularly those of the sixth Conjugation: For, this pair of Nerves, though they appear less than all others, at their first rising from the Brain; do yet hold a commerce with all other nerves of the whole body, and are immediately derived to more parts, than any other pair or Conjugation, which is the reason why Anatomists called them, the Wand'ring or Dispersed pair. And the Commerce they maintain with so vast a multitude of other nerves, is founded on a threefold relation or intercourse, viz. Complication, Consociation, and Inoculation: all which are largely described by Fallopius, and after him by our excellent Dr. Glisson. 
in observat. Anatomic. de Anatom. Hepatis. p. 436.  Now, if we seriously consider the scope or design of Nature, in all those laborious and curious Connexion's of Nerves, we shall find none, wherein our reason may with so much satisfaction acquiesce as in this, that they conduce to the commodious reception of the Nutritive juice and transportation of it to the principle of its Dispensation. For it seems, the Nutritive juice is first imbibed by the small branches of the Nerves of the sixth Conjugation; and those, though very many, being yet too few for the transportation of so large a quantity of that rich Nectar, as is required to the nourishment of the whole body, Nature hath conjoined with them a vast number of other Nerves, as Auxiliaries in that great work. So that it is not dissentaneous to reason, to conceive, that by these Nerves and their Coadjutors, the Succus Nutritius is carried to the brain and Spinal Marrow, thence to be afterward derived to all parts for their sustenance.  
Concerning the Fourth, 
What is the Motion of the same in the Nervs; viz. not continual, nor vehement: but by intervals, and slow and gentle; to the brain, in sleep, and from it to the members, after sleep.  viz. the Motion of the Succus Nutritius in the Nerves; though it be a problem of great obscurity, yet doth the light, let in at the postern gate of Conjecture discover thus much, that it is not continual (as that of the blood in the Arteries and veins) but by intervals; nor violent, but slow and gentle; as the defect of any swelling on either side of a Nerve bound about, in a living creature, doth sufficiently manifest. Nor is it unreasonable to conceive, that in a short time after each meal, immediately upon the distribution of the Chyle through the Venae Lacteae, the Succus Nutritius is imbibed by the Nerves of the sixth Conjugation, and by them carried to the brain and Spinal Marrow. Which perhaps, is the reason, why always, within an hour or two after meat, we perceive a certain dulness in our heads, together with an indisposition to motion, and a propensity to sleep, according to that proverb, When the belly is full, the bones would be at rest: and soon after, all those vanish again, and we perceive ourselves more light, strong, and active than before our refection; because then the nourishment gins to be diffused from the principle of Dispensation, of outwards into the limbs and other parts of the body. And with this opinion agrees that observation of Bartholinus that the Lymphducts are more plainly discernible about five or six hours after meat, than at other times; as being at that time more filled with the superfluities of the Succus Nutritius. Nor is it improbable, that the Brain and Spinal Marrow are chief nourished in sleep, and that then the Nutritive Liquor is usually carried to them, relaxing them with its sweet and mild vapours, and so both inducing and prolonging sleep. From whence perhaps it comes, that after long sleeps, we perceive our brains to be oppressed and beclouded with vapours, our senses dull, and the motive-faculty enervated. Besides, in sleep all motions of humours flowing to the patts by the Nerves, seem to be suspended; and yet the Circulation of the blood is certainly at that time more free and quick, than while we wake: So that It cannot be thought the cause of that cessation, but the Nerves only, which intermit their office of distributing the Succus Nutritius, during sleep. And all this will appear more reasonable, if we reflect upon the flux of humours in the Nerves immediately after sleep. For, then the Brain and Spinal Marrow re-contract themselves, and become more tense; so that the Nutritive liquor is from thence transmitted, partly to the members to be nourished, and partly to the Glandules; as well such as serve for the excretion of its absolute Excrement, as those that serve for the reduction of its relative, viz. it's acrimonious parts, that are returned into the blood, for the reason formerly mentioned.  
And concerning the Last, 
And what the Causes of that Motion, viz. the motions of the Diaphragme, of the Brain, and of the Nerves themselves.  viz. the Causes of this Motion of the Succus Nutritius; we may be allowed to conceive (at least, until Time shall have dispelled that Obscurity, which yet surrounds this abstruse Theorem, and the industry of some more dextrous Anatomist pierced deeper into the mystery of the Nerves; a subject not much less inscrutable, than the Nature of the Soul itself, which useth them as her principal instruments: we hope, we may have the liberty to conceive) that the Succus Nutritius is not imported to the brain and Spinal Marrow, nor exported from thence to the members, by any Attraction similary or Elective, against which we have formerly alleged convincing arguments, unnecessary to be here repeated: but, as the blood, and indeed all other humours of the body are moved, by mere Impulsion, or Protrusion, the immediate Cause of all motions in Nature. And the Agents, in this case impelling, we conceive to be the motions of the Diaphragme, of the Brain, and of the Nerves themselves.  
For since the Depression of the Diaphragme, is generally admitted to conduce to the distribution of the Chyle out of the stomach, guts, Venae Lacteae, common Receptacle, and Ductus Chyliferi, successively into the subclavian Vein: by alternately compressing all those parts, and so compelling the Liquor contained in them, to flow upward; and indeed to all other Natural motions; why may not the same be thought sufficient also to the Expulsion of the Nutritive juice, both out of the Praeparing Glandules, into the Nerves of the Sixth conjugation and their Auxiliaries, and out of them into the brain and Spinal Marrow; their position being such, as renders them no less subject to compression, by the descending Diaphragme, than the Venae Lacteae, common Receptacle, and other Chyliferous parts are?  
If this seem difficult, we may have recourse to the reason of the ascension of a liquor from the bottom through all parts of a sponge, cloth, or other filamentous substance (as is experimented in the percolation of Aqua Calcis, made by a long piece of woollen cloth, whose one end is dipped in the water, and the other hung over the brim of the vessel containing it) which we have professedly explained in the 356 page of our Physiology; and seems to be the same with the reason of the ascension of the nutritive juice of all plants from the roots to the top of the branches.  
And as for the Motion of the Brain; though it may seem to be no other, but what is impressed upon the brain, by the Pulsation of the Arteries (ascending from the Plexus Arteriosus mirabilis chief to the Dura Mater, and copiously disseminating themselves upon it); yet, since it is credible, that the Pulsation of the arteries doth promote the flux of the liquor in the Nerves, in other parts, especially such, where Nerves are either contiguous, or near enough to Arteries, to participate of their impulse: why may not the motion of the Brain also, to which the Nerves are continued, serve to ex-press the liquor out of them, toward the parts wherein they are terminated? Besides, it is most certain that immediately after sleep, the whole Brain, together with the conjoined network of its Nerves, becomes more tense and firm, than in sleep, which seems to render it moist and lax: and since that Tension cannot but in a manner ex-press, or squeeze forth, the liquor contained in the original of the Nerves, it is reasonable to conceive, that the motion of the Succus Nutritius from the brain to the parts, is to be imputed thereunto; especially it being by us observed, that the diffusion of the nourishment is chief soon after we awake and rise from sleep.  
And lastly, as for the Motion of the Nerves themselves; nothing is more manifest, than that, while the Nerves and Muscles are distended in Voluntary motion, the juice contained in the Nerves must be impelled or ex-pressed to the parts, into which they are inserted; the extension of any nervous body, necessitating the flux of any liquor contained betwixt its filaments, from one extreme to the other.  
But, this we deliver, not as doctrine, but mere Conjecture. Nor should we have adventured to deliver it, but that we hope, that as the singular obscurity of the Argument may incite some other more able brain to labour in the same scrutiny; so it may excuse us, if we have not been so happy, as to light upon the knowledge of the true Causes, we sought after; there being among Candid Spirits, not only pardon, but even commendation, due to ingenious Errors; especially in things of Difficulty, and where the discovery of Truth is to be hoped rather from Time and multiplied Observations, than from the single felicity of Witt.   

OF VOLUNTARY MOTION, Exercitation the Eleventh.  
Of Voluntary Motion, or the Use of the Muscles.  
FRom one Use of the Nerves, 
Article  viz. the conveying of the nourishment to all parts requiring it; 
The Inference, and Method of this discourse.  we now transfer our contemplation to the other, viz. the transmission of the Animal Spirits from the Brain the principal throne of the Soul, where she judgeth of the good or evil of objects; and from whence she dispenseth her commands) to the Muscles, the immediate and proper instruments of Motion Voluntary: and here, for the more perspicuity, we shall take the liberty of permitting our Curiosity to exspatiate itself a while in that delightful and ample field, the admirable Art of Nature shown in the Structure of those organs, in their Variety, and in the Reason of their Motions.  
The things required to Voluntary Motion, 
Requisites to Voluntary motion.  are (1) the object communicated by the sense to the judicatory Faculty, or Soul; (2) the Soul perceiving that object, judging it to be good or evil, and accordingly pursuing, or avoiding it; (3) the Instrumentum Mediatum, by which the Soul impresseth a motive-Faculty upon the Muscles, and immediately acteth, toward the attainment of her end; and (4) the Instrumentum Immediatum, by which immediately the motion intended is executed or effected.  
Concerning the Exciting Cause, 
That the Animal Spirits are the Mediate Instruments, by which the Soul moves the Muscles; argued from  or object; and the primary Agent; there is, nor can be no dispute: it being most evident, that the Soul is the principle of Motion, and that it is excited thereunto by the good or evil appearing in the object. But, concerning the Instrumentum Mediatum, or that by which the Soul doth cause the Muscles to move either the whole body, or some member of it, in order to her embracing, or avoiding the object; many, especially of late years, have seemed very much to doubt. To satisfy them, therefore, in this particular; we (with all the Ancients) conceive, that the Animal Spirits sent from the brain, by the Nerves, into the Muscles, are the Immediate instrument of the Soul, whereby she doth impress an actual motion upon the Muscles: and to evince the probability of this opinion, we offer these few, yet (in our judgement) weighty Reasons.  
(1) Voluntary Motion being nothing, 
the Mutation of Figure both in the Muscle and Member moved:  but the willing translation of the body of an Animal, or some part of it, out of one place, into another; it is necessary, the member moved should measure the determinate space betwixt the Terminus à quo, and the terminus ad quem; and consequently, that the proportion of the member moved, be answerable to the proportion of that intermediate space: now from that necessary proportion, there ariseth a change of Figure, as well in the member moved, as in the Muscle moving (as we shall ere long demonstrate by Principles Mathematical, in explanation and confirmation of the doctrine of our Master Galen, in 1. de motu Musculor. cap. 8.) but that Mutation of Figure in the external instrument, cannot arise immediately from the Soul itself: which being Immaterial, can of herself produce no such effect: and therefore it must arise from something more proportionate to the immediate energy of the Soul, than either the grossness of the member, or muscles ordained to move it, will admit them to be; which Something can be no other, than the Animal Spirits, whose subtlety makes them to approach nearer to the nature of the Soul, and whose sudden influx through the Nerves, into the body of the Muscle, causeth a swelling or distension, and so a contraction thereof, and consequently a change of Figure in the member.  
(2) Since every Instrument ought to be accommodate, 
the Quickness of voluntary motion.  as well to the nature of the Agent which is to use it, as to the effect to be produced by the use of it; and that Voluntary Motion is performed as it were in an instant and by a most swift and speedy Impulse from the soul; it followeth, that betwixt the incorporeal Agent, the soul, and those corporeal instruments, the Muscles, there must be some Intermediate instrument, such as is capable of being so transmitted from the Brain, into the Muscles, with the greatest velocity imaginable, and of setting them instantly awork, according to the determination and direction of the soul. Now, no part of an Animal can be thought capable of such easy and expedite Mobility, but the spirits, which flow through the body in less than the twinkling of an eye: and therefore, we conclude, that They are the Immediate instrument of the soul, in voluntary motion; according to the assertion of Galen (in 4. de locis affect cap. 6.) in these words; Est in cerebri ventriculis Spiritus, Animae primum instrumentum, quo & sensum & motum per universas corporis partes Anima transmittit, etc.  
(3) As the Power or Faculty of Seeing doth not reside in the Eye, 
the conquest of the acting Muscle, over its Antagonist.  nor that of Hearing, in the Ear, &c. but is imparted to the organs of sight, and hearing, from the soul, by the mediation of Nervs and Spirits: so likewise is not the Virtue Motive inhaerent in the Muscles, but communicated to them upon occasion, from the same soul, and seems to consist wholly in the quick afflux of spirits, as that by which alone they are moved. Which Galen also doth not obscurely intimate (in 1. de mot. Musculor. cap. 8.) where he saith, Aequipollens musculorum motus fit, quando neuter tonum Animalem habet auxiliarm; non aequipollens verò, cum alter solus dominatur: quare necessum est, ut vincat contractio istius musculi, qui ab Animali Facultare adjuvatur. For, what can be understood by this Tonus Animalis, or Facultas Animalis, unless it be the distension of the conquering muscle by Animal spirits, sent from the brain, at the pleasure of the Soul?  
(4) What's the reason, 
the swelling of each Muscle, when it moveth.  that a muscle is never moved, but it becomes more hard and swelling in the middle, than before (as is most evident in both the Masseter and Temporal Muscles, when we chew our meat) unless because it is then filled and distended with a greater gale of spirits, issued out of the store-house of the Brain? For, it seems more reasonable, that this swelling in the body of the Muscle is the Cause of its Contraction; than, on the contrary, that the Contraction should be the cause of the Swelling, as those contend who would have the motion to be performed without the afflux of spirits.  
(5) If a Nerve be cut asunder, the Muscle into which it was inserted, 
the privation of motion in a Muscle, whose Nerve is cut off.  doth for ever become uncapable of motion; and this, certainly, for no other reason, but because the intercourse of the spirits betwixt the brain and that particular Muscle is wholly destroyed. So that we may well conclude, that the Soul cannot cause voluntary motion, but by the distribution of Animal spirits, through the Nervs, into the Muscles.  
The necessity of Animal spirits, as the Immediate Instrument of the soul, thus appearing; we are next to speculate the Conditions requisite in the Immediate Instrument of the Motion itself: that so we may come to a clear understanding both of the structure and diversity of the Muscles, and at length of the reason of their moving the members, the thing at which our Scrutiny is chief leveled.  
As for the requisite Conditions, therefore, of this last Instrument, we observe,  
(1) That in an organ of voluntary Motion is required such a Constitution, 
why a Muscle is composed for the most part of Flesh.  as may render it fit to receive the Animal spirits, at the pleasure and command of the soul. Which makes it manifest, that a hard, inflexible, and bony substance is most incompetent to an instrument of motion; for which reason, perhaps, Galen adventured to affirm, that any part made hard and stiff by a thick Cicatrice, becomes unfit for motion: and that it must be such a part, as being soft, rare, spongy, and flexible, and distinguished with multitudes of Fibers, may most easily and readily admit the Gale of spirits flowing into its substance, and be by them filled or distended. Which is the reason, why the substance of the Muscles is for the most part Fleshy; than which no part, is more soft, rare, flexible, and distendible: as Galen hath observed (in 1. de usu part. cap. 13.)  
(2) Lest the spirits might flow into this flesh, 
of a Nerve.  indeterminately or at random and scatteringly: there ought to be such peculiar vessels or Conduits, which being continued from the brain or spinal marrow, quite home to the Flesh, into which they are inserted, may both carry the spirits thither, and preserve them from straying or dispersing by the way; and by which the Soul, or Regulating Faculty, principally residing in the brain, the original of the Nervs, may rule the members, as a Coachman rules his horses by the reins of his bridles; that we may use the same comparison with Galen, (1. de mot. musculor. cap. 1.). Now, the Nervs being the only parts of the whole body thus qualified, Nature most wisely inserted one, or more of them, into each Muscle. So that from this constitution of the Nervs, it appears, that they make the second Essential part of a Muscle. Nay, according to strict truth, we may adventure to say, that the Flesh and Nerve are the principal ingredients required to complete the essence of a Muscle: because there are some Muscles (viz. those of the Temples, of the Forehead, of the Eyes, of the Bladder, of the Fundament, etc.) in whose bodies are neither Tendons, nor Ligaments to be found, but only Nervs, and Flesh distinguished with various Fibres.  
(3) Because in some Members, 
Of a Ligament.  by reason of their Gravity, there is a greater resistance to motion, than the Musculous Flesh (in respect of its softness and tenderness) is able to overcome; therefore ought there to be an addition of some stronger and tougher substance, which being connected or united to the Flesh of the Muscle, may both corroborate the same, and firmly conjoin it to the bones, so as to enable it to move the ponderous member, to whose bones it is fastened. Now, this Nature foresaw, when she furnished some Muscles with Ligaments, especially such as were ordained to bear great stress, in moving the greater and more weighty members. Which Galen most elegantly expresseth thus; Ut enim ossa, quae dearticulantur, exactè simul ligarentur ac continerentur, ne facilè in motibus vehementioribus à sese abrumperentur; Ligamentum, quoad maximè potuit, durum, atque ab injuriis remotissimum efficere oportuit: ut autem ossibus à Musculis tractis promptè obsequeretur, molle rursus esse oportuit, atque ob id ipsum imbecillum. Atqui, forte quidem imbecillo, ac durum molli est contrarium. Quaenam igitur fuerit in his Naturae solertia, quae corpus invenit, quod commoditatem utramque haberet, idemque ab injuriis tutum esset; ex ipsad Anatome discas, licet, etc. 12. de usu part. cap. 2.  
(4) Besides the connexion of the Musculous Flesh to the bone, 
Of a Tendon:  by the mediation of a Ligament, there must be also something to render it prompt, easy and agile in its motion, so as to answer the celerity of the influx of the Spirits, and to fulfil the command of the Soul, as it were in an instant. Which Nature reflecting upon, superadded also a Tendon, or Chord, which in respect both of its subtlety, and of its tough and strong Contexture, or substance, and also of its connexion to the joint, doth make the motion more facile and quick, than otherwise it could possibly be; as appears in the Muscles of the Hands and Feet, etc.  
(5) That these parts named, viz. the Flesh, 
of a Membrane investing it:  Nerve, Ligament and Tendon, might not be endangered by lying uncovered or confused; therefore hath Nature clothed the whole Muscle with a proper Membrane or Coat: which hath these two further Uses, that it causeth the Muscles that are contiguous, to slip up and down easily and without enterfearing each other, and preserves the spirits immitted into the body of the muscle moved, from passing quite through, or dispersing themselves, which they are apt to do, both in respect of their subtlety, and of the force of their impulse.  
(6) And last, 
and of Arteries and veins.  since this organ of voluntary Motion is to be continually supplied with life, as being pars corporis vivens; therefore is it provided of Arteries and veins: those to bring in the vital blood, by whose irradiation all parts of the muscle are made participant of life; and these, to return the blood to the Heart, therein to receive a new impression of life.  
Now, 
That a Muscle is the Immediate Organ of Motion Voluntary.  seeing that in the whole body of an Animal, there is no other part that hath any the least title to this Description; it is undeniable, that a Muscle is the adequate or proper and immediate instrument of Motion voluntary: and may conveniently be defined to be, A part of an Animal, endowed with life, composed of a Nerve and Flesh, and frequently also of a Ligament and Tendon convered with a membrane, and so framed to be the proxime organ of voluntary Motion. And thus much of the Structure of the Muscles.  
As for the next Considerable, the Differences of the Muscles; they are many, as being desumed from their substance, quantity, figure, situation, original, insertion, Fibres, parts, Use and Action.  
In respect of their Substance, some Muscles are mostly composed of Flesh, 
Differences of Muscles, in respect of their substance.  as the Sphincters, and the Muscles of the Tongue: others are mostly Nervous and Membranous, as the Fascia la●a abducing the leg, etc.  
In respect of Quantity, 
Quantity;  which comprehends the 3 dimensions of Longitude, Latitude, and Profundity. Some are Long, as the Musculus rectus of the Abdomen, the Thylers' Muscle in the thigh: and others short, as the Musculi pyramidals in the bottom of the Abdomen. Some are Broad, as the Obliqne and Transverse Muscles of the Abdomen, the Latissimus dorsi, brachium deprimens, &c: others Narrow, as the Muscles of the Fingers and Toes, etc. Some Thick, as the two Vasti, or Huge Muscles in the thigh: others Thin and slender, as the Musculus Gracilis bending the leg, etc.  
In respect of Figure, 
Figure;  some are Triangular, some Square, some Pentagonal, some Pyramidal, some Round, some Oblong, and others of other shapes; as the Muscles Deltoides, Rhomboides, Scalenus, Trapezius, etc.  
In relation to their Situation, 
Situation;  some are Right, some Obliqne, some Transverse (understand it in respect of their Fibres) some Above, some Below, some on the right side, some on the left, some before, and some behind. Where we may note in the general, that obliqne muscles serve to obliqne motions, Right to exact Flexion, or Extension; and such as are seated within, conduce to Flexion; and such as are posited without, to Extension.  
In respect of their Original; 
Origination;  some arise from Bones, and that either from the Heads of them; as most of the greater Muscles; or a little below, or from the Glene, some sinus or small hollowness in the bone: some only from one single bone, some from two or three: some from Cartilages or Gristles, as the Muscles proper to the Larynx: some from the Membrane enshrouding the Tendons, as the Musculi vermiculares: and others from other parts, as the Sphincters of the Bladder, and Fundament.  
Their Insertion considered; 
Insertion;  some are inserted into Bones, some into Cartilages, as the Muscles of the Eyelids, and of the Larynx; others into a Membrane, as the Muscles moving the Eyes; others into the skin, as those of the Lips: some arising from divers parts, are inserted only into one; and on the contrary, some arising only from one part, are terminated in many.  
In respect of their Parts 
Parts;  (by which we must now understand not only such, whereunto as chief ones every Muscle is divided, but those also upon which it is seated); there are various differences. The parts into which each Muscle is commonly divided, are the Head, or Beginning; the Belly, or Middle; and the Tail, or Tendon. Most Muscles have but one Head; yet some have two, others three: whence they are called Bicipites, and Tricipites. Most have but one Belly, yet some are double-bellied, as the Muscle shutting the lower jaw, of the Bone Hyoïs', whence they are named Digastrici. The Tendons of some are broad and membranous; of others, round; of others, short; of others, long; of some, perforated; of others, entire; of some, single; of others, multiplied. Sometimes you shall find many Muscles ending in one and the same Tendon; as, in the Leg, the Gemelli or Twin-Muscles, and the Solaris, are united into one Chord. Lastly, from the parts upon which they are seated, they sometimes borrow their names; as the Crotaphitae, or Temple-Muscles; the Rachitae, or Spinati of the back; the Iliaci, etc.  
According to the variety of their particular Actions, 
and Actions.  the Muscles admit of a triple Difference. Whereof the First is, that some are Congeneres, or Confederates, which both conspire to one and the same motion; as when two are Flexors, two Extensors; one possessing the right, the other the left side of the member: and others Antagonists, which have motions contrary to those of others; there being scarce any one Muscle, which hath not its Contrary, or Opponent; as to every Flexor is opposed a Tensor; to every Elevator, a Depressor; to every Adductor, an Abductor; excepting only the two Sphincters, and the Cremasters. The Confederates are generally equal in magnitude, number, and strength: the Antagonists not, but different, according to the weight of the part to be moved, and the vehemence of the motion. Thus, the Muscles bowing the Head, are only Two; while there are Twelve to lift it up; and those that shut the lower jawbone with the upper, are many, but those that open it, are only two; for the weight of heavy bodies doth facilitate their falling down. The Second is, that some Muscles move only Themselves, as the two Sphincters: others somewhat else besides themselves. And the Last respecteth the peculiar motions of particular Muscles; whence some are called Benders, some Extensors; some Elevators, others D●pressors; some Adductors, others Abductors; some Rotators, some Circumactors, some Masseters or Eaters, some Cremasters or Hangers, some Sphincters or Constrictors, etc. And thus much concerning the several Differences of the Muscles.  
As to the Reason and Manner of their Motion (an Argument, as singularly delightful, 
That the Reason of the motion of the Muscles, cannot be explained, without having recourse to Mathematical principles.  so singularly difficult) forasmuch as the Locomotion of the whole body, or any one member of it, being considered per se, merely as Motion, without reflecting upon the end of it, seems to be an effect purely Mathematical, as well because it is a Commensuration of the length of the space betwixt the Terminus à quo, & ad quem, as because it is a resistance and overpowering of Gravity: therefore shall we lay down some few Mathematical principles, of plain concernment in the explication of it, such as without which our disquisition into the nature of Voluntary Motion would be obscure and unsatisfactory.  

Fundaments Geometrical. 
Principles Geometrical, of necessary importance toward the understanding thereof.   

Proposition, 1.  
What are equal to the same, are equal also among themselves: & è contra.   

Proposition, 2.  
All right lines drawn from the Centre to the Circumference, are equal.   

Proposition, 3.  
Two right lines whatsoever, mutually cutting each other, make, at the vertex, Angles equal among themselves.   

Proposition, 4.  
The squares of equal lines, are equal.   

Proposition. 5.  
A right line, falling upon two right lines aequidistant, or parallels, makes equal Angles.   

Proposition, 6.  
In Triangles, where the Angles are equal, the sides also are equal and proportional.   

proposition, 7.  
In a Triangle, where any one Angle is greater; there the side subtending that Angle, is also greater.   

proposition, 8.  
In every Parallelogram, the Compliments of those Parallellograms, that are about the Diameter, are equal among themselves.    

Demonstration.  
 
Suppose A B C D the Parallelogram; A D, the Diameter or Dimetient; and the supplements H B, and H C. We say, the supplement H B. is equal to the Supplement H C. because the Parallelogram hath for its Diameter A D: and therefore the Triangle A B D. is equal to the Triangle A. C D. Again, because AEGH. hath its diameter A H. therefore the Triangle A G H. is equal to the Triangle A E H. By the same it is demonstrated, that the Triangle H F D. is equal to the Triangle H I D. Now, since the Triangle A G H. is equal to I D; and E H G. equal to F D I: it follows, that the supplement H B. is equal to H C. Which was to be demonstrated.  

proposition, 9  
If a straight Line be divided into parts equal and unequal; the Parallelogram, that is contained in the unequal segments of the whole Line given, together with the square of that which is between the segments, will be equal to the square described by the half Line.  
   

Demonstration.  
 
Let the right line be A B, divided into equal parts, at the point C; and into unequal, at the point E. Let from the point A, to the proportion of the equal segment, be made a square A C G H; and from the point E, on the unequal segment, be drawn a parallel line E F; and from the point A, the Diameter or Dimetient A H; and a parallelogram E F B D. We say, the Parallelogram E D. with the square F H. is equal to the square A H: which is proved from the Antecedents.  

proposition, 10.  
To make a Square equal to a Parallelogram given.  
Let the Parallelogram be A B C D. To which to find a square equal, draw a line from C to E, to the proportion of G D; and divide A E into equal parts into the point F. from whence make a circle A G E; and continue the line C D to the point H. We say, the Line C H. is the root of the square I K C H. which is in equal proportion to the Parallelogram A B C D.    

Demonstration.  
Because the Line A is divided into equal parts at the point F. and into unequal parts, at the point C; and the Parallelogram contained in the unequal segments, together with the square FC, is equal to the square FH. or FE. the equal segment, according to the ninth proposition precedent: it follows, that the Parallelogram ABCD. is equal to the square IKHC. according to the 47. proposition. 1. lib. of Euclid. Which was intended.  
Fundaments Architectonical, out of Vitruvius, 
Principles Architectonical, of the same Concernment.  lib. 10. cap. 8.  

Proposition.  
1. In the Centre all Gravity ceaseth; so that therein nothing is either Heavy or Light.  
2. The power of all Motion is varied, according to the ration of the Centre to the Circumference.  
3. By how much the more remote or elonged from the Centre, any thing is; by so much the swifter is it moved.  
4. By how much greater the Circumference of the Circle, so much greater the Diameter, and so much swifter the Motion.    

Demonstration.  
Let the Centre be E. from which under the Diameter E F. let the weight be placed at F. We say, this weight at F. doth not rest there, but moveth to its Centre, towards C. Again, if the same weight be elonged, or removed to A; then by reason of its greater distance from E, and of the greater Circle; it will be moved towards its Centre C, with the greater velocity accordingly.  
5. Bodies equal, and under the same Diameter▪ equally distant from the Centre; do cut a perpendicular Line at right Angles.   

Demonstration.  
In the former Scheme, let one body be at B, and another at A. upon the Diameter of the Circle, whose Centre is E. and neither of them shall move, because their Gravity is equal, in that proportion of the Diameter, and so hasten to the Centre C. with equal swiftness; but, because they make equal Angles with the perpendicular DE.  
6. If to one of two equal bodies, placed under the same Diameter, and equally distant from the Centre, any weight be superadded; that, whose weight is increased, shall move more strongly, and make an acute Angle with the perpendicular, or wholly obtain the place of the Centre: as in the last Scheme, the weight A is increased to the magnitude G; and therefore it must move the more strongly; as is evidently concluded.  
And let these suffice for the Fundamentals.  
To come to their Concernment in the Motion of the Muscles, we observe, that every Muscle hath a twofold Motion, viz. one Natural, wherein the Fibers of the muscle spontaneously recontract themselves, after they have been extended, or restore themselves to their native tenor; 
That every Muscle hath a Twofold Contraction, viz. Natural and Animal.  by Philosopher named, the motion of Restitution, common to all Tensile bodies: and this is always from the end, towards the beginning of the Muscle, according to the position of its Fibers: another, Animal; wherein the same Fibers are further Contracted, by the forcible and copious influx of Animal spirits, at the command of the soul, in order to the performance of some action intended.  
That the Natural Contraction of a Muscle, is not sufficient to voluntary Motion, 
That the Natural Contraction is not the cause of Voluntary Motion; but only the Animal.  though we allow every muscle to be made upon the stretch, i.e. in an extended position, is manifest from hence, that betwixt each Muscle and its Antagonist, there is an equal power of naturally-moving themselves toward their originals; so that betwixt two Contrary forces, the one drawing one way, the other the clean contrary, the member must be held immovable; as appears in the 5th. proposit. Architectonical. Necessary it is, therefore, to voluntary Motion, that one Muscle overpower the other, not by reason of its spontaneous or Natural Contraction, but of its impressed or Animal; which depends upon the supply of spirits transmitted from the brain, by the Nerves into the Fibers of the acting muscle, and so-distending. them, as to cause the whole Muscle to shorten or contract itself. And, that the power of Antagonist is, as we affirm, naturally equal; may be concluded from hence, that if one Muscle be cut off, its Antagonist instantly draws the member to its side, which before was held in the middle, and as it were aequilibrated betwixt them.  
Secondly, we observe; that in all Motion there are two Terms to be acknowledged, 
That in Motion, are Two Terms, one Fixed, the other Movable; the last of which is sometimes more, sometimes less remote from the former, according to greater or less resistance of Gravity in the member to be moved, and vehemence of the Motion.  the one is the point of Rest, or the Fundament, in which the muscle is firmed or fastened, because all motion is super aliquo Quiescente: the other is in part Mobili, or insertion of the muscle, from whence the Muscle, by contraction, draws the member toward itself; and this is sometimes less, sometimes more remote from the Centre, or point of rest, according to the less or greater resistance of Gravity in the member to be moved, and according to the less or greater vehemence required to the motion. Which Nature (whose Art is not more admirable in any thing, than in her proportioning the length of the insertion of each muscle, from the Hypomochlion or point of Rest, to the Gravity of the member to be moved) respecting; most ingeniously contrived a way to compensate the slender strength of divers muscles, by inserting them at great distance from the Centre of their motion, or that point, about which the member is to be moved. For, since (according to the 1. proposit. Architectonical) there is no motion in the Centre; we may easily understand, why in many muscles, ordained for strong motions, the Terminus stabilis, or original, is more remote from the Terminus Mobilis, or insertion, than in others framed for motions less strong; viz. that by even a small force, the muscle (which, considered in its proper bulk, or in any other position, would be insufficient to the effect designed) might elevate a great weight, as we see in the muscles of the Hand, Arm, Thighs, and other parts. For this reason also is it, that in some bones we have certain prominences, or Butting forth in the end, called Epiphyses, and Apophyses, to which the muscles are fastened. The truth of all which is evinced by the 2d and 3d proposit. Architectonical.  
These things being thus firmly established, it appears an undeniable truth, 
No Motion without change of Figure.  that no motion can be made, without changing the Figure of the muscle. For, since equal Angles subtend equal sides, by the 6th Geometrical Proposition: it follows necessarily, that in all motion, the Figure of the member moved, is changed.  
And, because the change of Figure doth depend on the change of Angles; 
Which is Threefold, respective to the difference of Angles.  therefore must we admit a threefold Figure, as there are three sorts of Angles, viz. (1) a right, in which neither of the two opposite muscles acteth; (2) an obtuse, which being greater than a right, is consequently subtended by a greater side; and (3) an acute, which being less▪ requires a less subtending line.  
Now, forasmuch as in the Middle Figure, no motion can be made, 
All motion is made in one of the Two Extreme Figures; and how, demonstrated.  because then both the opposing Muscles are equally extended: we are to demonstrate, how it is effected in both the Extremes. And this, certainly, is done, when one of the acting Muscles is filled or distended by the Animal influx, more than its Antagonist, whereupon the Figure of the Conquering muscle is changed; and the Angle of Articulation is made more Acute, or less, by that Contraction; and that segment, detracted from the line, is in proportion to the space comprehended. For Example.   

Demonstration.  
Imagine the Brachium, or upper half of the Arm, from the shoulder to the elbow, to be G A; and the Cubit, or lower half from the elbow to the hand, to be A B: the Muscle bending the Arm, to be C F: and its Antagonist extending it, to be C G: and the object to be apprehended by the hand, D. Now, we say, while those two opposite Muscles G F. and C G. are equally contracted, the Appetite must fail of being satisfied, i.e. the hand cannot be brought to lay hold on the object desired; because the Figure or Angle of Articulation remains invariable. But, that the hand may be raised to the object, it is necessary, that Angle should be made more Acute, by contraction of the Muscle C F. in proportion to the motion of the line B D: and because that Angle is less, therefore is the line subtending it also less, or shorter; according to the 5th and 6th proposit. Geometrical. And, since the Line E F. is in proportion to the Line D B: it follows that so much is to be detracted from the length of the Muscle: yet, we are not to suppose, that this detracted portion of the Muscle is to be wholly cast away; in regard, than it would be uncapable of the like or any other motion ever after: but, that being plumped up or filled with a gust of spirits, it is incurvated, or made Convex by that distension; and that line, which before was straight, is now changed into an Arch, and consequently made shorter.  
Moreover, since there are 3 Dimensions, Longitude, 
That a Muscle, in contraction, is increased in Latitude and Profundity, proportionately to its diminution in Longitude; demonstrated.  Latitude, and Profundity; and that it is not any one, but all of these, that determine the Figure of a Muscle: it follows, that all Muscles, while they are contracted, are as much increased in Thickness and Latitude, as they are diminished in Longitude. Which may be naturally inferred from the importance of the 5. 7. 8. 9 and 10. propositious Geometrical; where a square is found equalto a Parallelogram.   

Demonstration.  
Let the Parallelogram be A B C D. representing the Muscle Biceps, of the Arm, as it is extended; and a Square equal thereunto, B E G F, representing the same Muscle, as it is contracted. We say, that the Muscle, in its second Figure, or Contraction, hath lost nothing of its bulk, that it had in the first Figure, or Extension: but, because the Square of the muscle, B E G F. is equal to the Parallelogramme, A B C D; therefore it follows, that the superfice of the muscle is the same, and that the part G D. changed in its Latitude, is in proportion to the Line A D. which determin's the Local motion.  
Reflecting upon what hath been said, we soon discover, 
The Necessity of Antagonist-Muscles.  why each Muscle generally hath its Antagonist; there being contrary motions to be performed successively by every member, and it being impossible, one and the same Instrument should suffice to both. Now of these Antagonists one doth bend the member, by Contracting itself; and the other by its contraction doth extend it: and both extend each other successively: that which is contracted, doth always act, and that which is extended, doth not act, but suffer, and is transferred with the part moved.  
But here we are to except some Muscles, which seem so sufficient to the motion of the part into which they are inserted, 
How Circular Muscles are Contracted.  as to have no need of Antagonists; as all Circular muscles, whose motion is easily understood from the mathematical principles premised. For, since a Circular muscle hath circular Fibres, and that all contraction is made secundum continuitatem lineae; it follows, that such muscles shut the part to which they are affixed, by contracting themselves toward their Centre; as may be observed in the Sphincters of the Bladder and Fundament, and in the Round muscle of the Eyelids.  
Only it may be enquired, Why those Sphincters have no Antagonists, 
Why the Sphincters have no Antagonists.  as the Clausor Palpebrarum seems to have, the Elevator opening the eyelids, as the Clausor shuts them? Whereof the Reason certainly is this, that both the Bladder and Fundament are not opened by muscles, but by the quantity of Excrements contained in them, which being pressed or detruded downward by the Diaphragme and muscles of the Abdomen, force open the Sphincters, by extending their Fibers from the Centre to the Circumference; so that to speak strictly, the excretion of the Urine, and of the Excrements of the belly, are not actions immediately voluntary, as the opening of the Eyelids is.  
And this is all we thought necessary to be said, concerning the Use of the muscles, 
Conclusion.  in general, and concerning the admirable Geometry observed by Nature in the Fabric of them.  
Should we extend our discourse, to the accommodation of the Figure and motion of each particular muscle in the whole body, to the Geometrical, and Architectonical principles premised: as we should abuse your Patience, so should we disparage your Capacity of making use of the same Clue for your guidance through the whole Labyrinth of Voluntary Motion, that we have put into your hands for your more easily entering into it. We shall conclude, therefore, with this due acknowledgement; that the Omniscient Creator hath made all things, as in the Greater World, so also in the Lesser, Man, in Number, Weight, and Measure.    

THE CONTENTS.  

Exercitation the First. Of Nutrition.  
A Art. 1. Nutrition and Generation, one and the same Act of the Soul, or Virtue Formative. fol. 1  
2. As well in respect of the Matter, as of the Efficient: 2  
3. The Necessity of Nutrition, twofold, viz. Augmentation, and Conservation. 3  
4. The vital Flame, the Efficient Cause of the Consumption of the substance of the parts. 4  
5. The Matter thereby consumed, not the solid substance of the parts, but the Fluid, and chief the Blood and Spirits. 5  
6. The Manner how they are consumed, is by contitinual Dispersion. 6  
7. And, in what Quantity: 7  
8. The Efficient cause of their Renovation, what, 8  
9 And what the Material. 9  
10. And the Manner how they are renovated. 10  
11. A Consectary, of the twofold Expense of the Chyle. ibid.   

Exercitation the Second. Of Chylification.  
Art. 1. The Order of the meat in the stomach. 11  
2. The posture of the stomach, in Concoction. ibid.  
3. The Dissolution of the meat, by an Acid Humour found in the stomach: 12  
4. Which causeth a certain Fermentation of the Chyle therein. 13  
5. All parts of the Aliment not chylified at once, but successiyely; and the first chylified, first discharged into the Guts. 14  
6. The Time required to perfect Chylification, various, according to divers respects. ibid.   

Exercitation the Third. Of the journey of the Chyle.  
Art. 1. The traduction of the Chyle from the stomach and guts, into the common Receptacle, through the venae Lacteae: 16  
2. Of which there are two Kind's, one arising from the Guts, the other from the Glandules of the Abdomen, into which the former sort exonerate themselves. 17  
3. But none of either kind tend to the Liver. 19  
4. That the Milk in the paps, is not made of Blood; but of mere Chyle, brought thither by some peculiar vessels: because ibid.  
5. There are no convenient conduits, by which blood can be brought into the paps, in sufficient quantity: 20  
6. Blood is not a fit, nor possible Matter, for the Generation of Milk: 21  
7. Milk and Chyle agree in all their manifest Qualities; and are reciprocally convertible. 24  
8. That Chyle is imported into the womb, in women with child. 25  
9 From the Authority of Hypocrates; and 26  
10 Of Dr. Harvey: 28  
11. And from the Sympathy betwixt the womb, and the paps. 29  
12. A conjectural description of the Chyliferous vessels tending from the paps to the womb. 31   

Exercitation the Fourth. Of Sanguification.  
Art. 1. The most part of the Chyle is converted into Blood: 32  
2. Not by an Organical, but Similary action. 33  
3. Whose primary Efficient, is not the Liver: 34  
4. Nor the veins; 36  
5. Nor the Heart; but the Vital Spirit, residing in the blood. 37  
6. Which alone formeth the blood, in a Chicken, out of the Colliquamentum. 40  
7. The Manner, how blood is first generated in an Embryo, by that vital spirit. 42  
8. In what part of the Conception it is first generated, viz. in the Chorion. 44  
9 In the generation of blood, what are the Concurrent Extrinsecal Causes, and what the Accessary Organical. 45  
10. The conversion of the Colliquamentum into blood, by the Heat and Motion of the vital Spirit; illustrated by sundry analogous' Experiments, and Observations. 46  
11. That the same Agent, which maketh the first blood in an Embryo, doth make it èver after in an Animal during life. 48   

Exercitation the Fifth. Of the Uses of the Blood.  
Art. 1. Blood; not the general Nourishment of the body: because 50  
2. The contrary opinion is subject to sundry both inexplicable difficulties, and irreconcilable incongruities: ibid.  
3. There are sundry parts, into whose substance blood is not admitted. 52  
4. Fat men generally have the least blood, and lean the most. 53  
5. Men perishing by Famine, have their arteries and veins full of blood. 54  
6. The blood continueth red and florid, in the habit of the body. 55  
7. Hypocrates cured a man of extreme Leanness, only by profuse phlebotomy. ibid.  
8. The blood is observed to be less unctuous and glutinous in the Arteries, that carry it to the parts, than in the veins, that return it from them. 56  
9 There is a manifest Dissimilitude betwixt the blood, and sundry parts of the body. ibid.  
10. The progress of Nutrition, is from crudity to Fusion and Volatility: not retrograde from Volatility to Fixation; and so the Aliment ought to be more crude or fixed, than the parts to be nourished. 57  
11. The blood itself is nourished, and consumes the substance of the solid parts: and therefore cannot be their nourishment. 58  
12. The First Matter, of which the parts are made, is not blood; but a certain liquid juice, very like the White of an Egg. 60  
13. Nevertheless, blood may be the nourishment of such parts, whose substance is mostly Sanguineous: and what those are. 61  
14. The Manner, how the Vital Heat is conserved, and the vital spirits continually recruited, ex Sanguine. 62  
15. The Reason of the Mication; or panting Motion of the blood, in the Arteries. 64   

Exercitation the Sixth. Of the Motion of the Blood, its Conditions and Causes.  
Art. 1. The Method of the whole Chapter. 66  
2. That the Motion of the Blood is Circular. ibid.  
3. From the vena Cava, into the right ventricle of the Heart: 67  
4. From the right ventricle, by the vena arteriosa, into the Lungs. ibid.  
5. From the Lungs, through the Arteria venosa, into the Left ventricle. ibid.  
6. From the Left ventricle, into the Great Artery, and thence into the smaller arteries. 68  
7. From the smallest Arteries, through the substance of the Flesh, into the smallest veins. ibid.  
8. How the New-made blood is circulated with the old. 69  
9 That more blood passeth through the Heart, in an hour, than can be supplied from the Chyle, in several days. ibid.  
10. The Necessity of this Circulation, inferred from three Considerations, viz. 70  
11 The Quantity of blood contained in the Heart, in its Diastole. 71  
12 The Quantity expelled out of it, in its Systole. ibid.  
13 The Number of Pulses, in an hour. 72  
11. That the Circulation is Universal, in all the Arteries and veins of the body. 73  
12. But, after a peculiar manner, in an Infant unborn. 75  
13. That this Motion of the blood is Continual: 76  
14. Vehement: 77  
15. Swift: ibid.  
16. Of equal velocity in the Arteries and Veins. 78  
17. The blood, not the Cause of its own Motion, in respect of any Motive Faculty inhaerent in it: 80  
18. Nor in respect of its Ebullition; ibid.  
19 Nor of its Rarefaction; 81  
20. But of its Quantity distending the ventricles of the Heart. 83  
21. The blood not moved by Attraction; 84  
22. Nor by Vection; ibid.  
23. But by Impulsion of the Heart, endowed with a Pulsifick Faculty; if any such may be admitted. ibid.  
24. The Fabric of the Heart, a remote Cause of the Motion of the blood. 87  
25. The Motion of the Heart described, as consisting of two contrary motions, and a Respite betwixt them: ibid.  
26. And the Figure of it in each. 88   

Exercitation the Seventh. Of the Depuration of the Blood.  
Art. 1. The Genealogy of the Excrements in the blood: 91  
2. Exemplified in the Distillation of Wine: 93  
3. The several sorts of those Excrements, and their Definitions. 94  
4. The Reason, why each particular Excrement is determinately imported into the part particularly comparated for its separation: 97  
5. Not that it is so directed by any Intelligence, or Distinguishing Faculty: 99  
6. Nor that it is Attracted by the like Excrement contained in that part: ibid.  
7. But, that there is a certain peculiar Conformity of the Magnitude and Figure betwixt the minute particles of this or that Excrement, and the pores of this or that part peculiarly constituted for the reception of it. 100  
8. Which is also the Cause of the Separation of particular Excrements, in particular parts. 101  
9 The Differences of Colatures, used by Nature, in the separation of Humours in the body. 102  
10. The Reason and Manner of the separation of the Serum, from the blood, in the Kidneys: 104  
11. Of the Phlegmatic Excrement in the stomach and Guts: 105  
12. Of the Bilious Excrement's accompanying the Phlegmatic so far. 106  
13. Why the blood is not carried immediately out of the trunk of the Vena portae into that of the Vena Cava; but through the various meanders in the Liver. 109  
14. And, why it is transmitted through the Parenchyma of the Liver. ibid.  
15. That the Parenchyma is the Principal part of the whole Liver: 110  
16. And a kind of Streyner; 111.  
17. Whose particles are contexed after a peculiar manner; and pores of ●ivers sorts: in respect whereof the Bile is therein separated from the blood, Mechanically. ibid.  
18. The same inferred from Four Considerables. viz. 112  
The equal distribution of the capillary branches of all the vessels of the Liver; ibid.  
The Pulsation of the vena portae within the Liver; 113  
The assistance of that pulsation, by the Hepatique Nerve. 114  
The Resuscitation of vitality in the blood, in the branches of the vena Portae, within the Liver, and a new Fermentation thereof, previous to the separation of the Bile. ibid.  
19 The various Manner of the Excretion of Excrements, after they are separated and collected. 116  
20. The particular Manner of the Excretion of the Bile: and 117  
21. The Cause thereof. 118  
22. Paradox; that we have a certain Natural Feeling, wholly distinct from the Animal, and independent upon the Brain. 119   

Exercitation the Eighth. Of Respiration.  
Art. 1. The Connexion of this discourse to the precedent. 126  
2. The Disparity betwixt Respiràtion and Pulsation, both as to their Times or Periods, and as to their Uses. ibid.  
3. Respiration described. 130  
4. The Efficient Cause of Inspiration, is the Dilatation of the Breast, impelling the ambient Aer into the Lungs. ibid.  
5. And the Cause of Expiration, is only the spontaneous Contraction of the breast. 132  
6. The Disatation of the Chest and Lungs, not from any Motive Faculty congenial to the Lungs: 133  
7. Nor from the impulse of the blood out of the Heart, into the Lungs: 134  
8. Nor from the motion of the Muscles of the Thorax: 135  
9 But, from the Diaphragme, moved by a congenite Faculty. ibid.  
10. Yet the Intercostal and Pectoral Muscles, are allowed to conspire with the Diaphragme, in respiration, violent and arbitrary. 137  
11. The Final Cause of Respiration, not the Refrigeration of the Heart, or Vital Flame; but, the subtiliation of the blood, which by the admistion of Aer, is made the more convenient fuel of the vital Lamp, and matter of the spirits. 138  
12. The same exemplified in the accension of flame in wood, by Aer blown out of Bellows: and 139  
13. inferred from the structure of the Lungs. 140  
14. The Use of Expiration. 141  
15. A Problem, of the respiration of the Foetus in the mother's womb. 142  
16. The motion of the Brain, not dependent upon Respiration, but upon the Pulsarion of the Arteries. 145  
17. The Secondary Uses of Respiration. 147   

Exercitation the Ninth. Of the Lymphducts.  
Art. 1. The Lymphducts a new and excellent invention. 149  
2. To whom the honour of their discovery is to be ascribed. ibid.  
3. Their Description. 150  
4. Differences. 151  
5. Origination. ibid.  
6. Insertion. ibid.  
7. Situation and Progress. 152  
8. Liquor, deduced partly from the Arteries, and 153  
9 partly f●●m the Nerves. 154  
10. The Uses of that Liquor. 155   

Exercitation the Tenth. Of the Distribution of the Nourishment through the Nerves.  
Art. 1. That the Nerves are vessels carrying the Nutritive juice to the parts; argued 156  
2. From the Atrophy or decay of Nutrition in parts affected with the Palsy, and whose Nerves have been wounded. 157  
3. From the beneficial use of Cephalique Emplastres, in Consumptions f●om ulcerated Lungs. ibid.  
4. From the Fatness of men endowed with large, open, and spongy Nerves. 158  
5. From the roscid Humour exstilling from wounds of the joints and sinews. ibid.  
6. From the Material principle of wenns and Scrofulous Tumours. 159  
7. From the Matter of the seed, and the manner of its preparation in the Testicles. ibid.  
8. From the Glutinous matter issuing from broken Bones, and cementing them together again. 162  
9 From the Unequal Nutrition of some parts in the Rickets. 163  
10. Three grand Difficulties troubling this opinion. 164  
11. Solution of the First, asserting the possibility of the flux of the Nutritive juice, through the Nerves, notwithstanding no manifest Hollowness be discernible in them. ibid.  
12. Solution of the Second, yielding the Reason, why no swelling ariseth in a Nerve, when bound with a ligature, in a living Animal. 168  
13. Solution of the Third, showing the Reason why the Nutritive juice is not found in the Nerves of dead bodies dissected. 169  
14. What is the Principium Elaborationis of the Nutritive juice; viz. the Glandules of the Mesentery, of the Loins, and the Thymus. ibid.  
15. What the Principium Dispensationis; viz. the Brain, and Spinal Marrow. 174  
16. What the Vessels importing the same into the Brain and spinal Marrow; viz. the Nerves, and particularly those of the Sixth Conjugation of the Brain. 175  
17. What the Motion of the same in the Nerves; viz. not continual, nor vehement: but by intervals, slow and gentle; to the Brain, in sleep, and from it to the members, after sleep. 176  
18. What the Causes of that Motion, viz. the motions of the Diaphragme, of the Brain, and of the Nerves themselves. 178   

Exercitation the Eleventh. Of Voluntary Motion.  
Art. 1. The Inference and Method of this Discourse. 182  
2. Requisite to Voluntary Motion: ibid.  
3. That the Animal spirits are the Immediate instruments, by which the soul moveth the Muscles, argued from. 183  
4. the Mutation of Figure both in the Muscle and Member moved: ibid.  
5. the Quickness of voluntary Motion: 184  
6. the Conquest of the acting Muscle, over its Antagonist: 187  
7. the swelling of each Muscle, when it moveth: 188  
8. and the privation of motion in a Muscle, whose Nerve is cut off. ibid.  
9 Why a Muscle is composed for the most part of Flesh; 189  
10. Of a Nerve; ibid.  
11. Of a Ligament; 190  
12. Of a Tendon; 191  
13. Of a Membrane investing it; 192  
14. And of Arteries and veins. ibid.  
15. That a Muscle is the Immediate Instrument of voluntary Motion. ibid.  
16. Differences of Muscles in respect of their (1) Substance, (2) Quantity, (3) Figure, (4) Situation, (5) Origination, (6) Insertion, (7) Parts, and (8) Actions. 193  
17. That the Reason of the Motion of the Muscles, cannot be explained, without having recourse to Mathematical Principles. 196  
18. Principles Geometrical, of necessary importance to the understanding thereof. 197  
19 Principles Architectonical, of the same Concernment. 201  
20. That every Muscle hath a twofold Contraction, viz. Natural and Animal. 203  
21. That the Natural Contraction is not the Cause of voluntary Motion; but the Animal. ibid.  
22. That in Motion are two Terms, the one Fixed, the other Movable, the last of which is more or less, removed from the Former, according to the greater or less resistance of Gravity in the member to be moved, and the vehemence of the Motion. 204  
23. No Motion without Change of Figure. 205  
24. which is Threefold, respective to the difference of Angles. ibid.  
25. All Motion is made in one of the two Extreme Figures: and how, demonstrated. ibid.  
26. That a Muscle, in Contraction, is increased in Latitude and Profundity, in proportion to its diminution in Longitude; demonstrated. 207  
27. The Necessity of Antagonist Muscles. 208  
28. How Circular Muscles are Contracted. 209  
29. Why the Sphincters have no Antagonists, ibid.  
30. Conclusion. 210   
FINIS.